<PAGE>   1


                                                                    Exhibit 10.1

July 28, 2000



Mr. Frank J. Amadeo
President
Estefan Enterprises, Inc.
420 Jefferson and 5th Street
Miami Beach, Florida 33139

         This letter amends the Agreement dated September 1, 1999 (the
"Agreement") between quepasa.com, inc. ("quepasa"), Estefan Enterprises, Inc.
("EEI") fso Gloria Estefan and Gloria Estefan ("Gloria") in light of the
postponement of Gloria Estefan's previously announced 2000 United States concert
tour. Capitalized terms not otherwise defined in this letter have the meanings
set forth in the Agreement.

         The Agreement is hereby amended as follows:

         1.  All references in the Agreement to quepasa's promotion of Tour 2000
             shall be deleted. Quepasa and EEI will work together to generate
             opportunities for Gloria to make appearances as a spokesperson for
             quepasa, including meet and greet sessions, promoted or arranged by
             quepasa in conjunction with Gloria's other scheduled appearances,
             concerts, and other public activities. The use of Gloria's name,
             image and likeness in print, radio and television advertising
             through December 31, 2000 may be included in advertising to support
             quepasa's Community and Educational Initiative (the "Initiative")
             as well as in connection with any contesting as contemplated by
             paragraph 7 hereof. As set forth in the Agreement, Gloria and EEI
             will not agree for Gloria to be a spokesperson for any other
             Internet company for the term of the Agreement and will not enter
             into any agreement of any nature that involves Gloria with any
             Internet company that is in competition with quepasa; provided,
             that this limitation does not apply to any other EEI artists or
             businesses.

         2.  Gloria will appear at one public event in connection with the
             Initiative in Los Angeles, California on or about September 13,
             2000. Gloria will also participate in one on-line chat session in
             association with promotion of the Initiative. Any and all aspects
             of Gloria's participation and involvement in such events must be
             reasonably mutually agreed upon by both parties prior to the
             commencement of the event.

         3.  In Section 1.A. of the Agreement, the requirement that one of the
             TV spots and one of the radio spots exclusively promote Tour 2000
             shall be eliminated, and quepasa shall not be required to include a
             five second tag promoting Tour 2000 in any of the TV or radio spots
             or to include panels promoting Tour 2000 in media advertising.

         4.  The last bullet point in Section 1.C. shall be amended to provide
             that quepasa will have the exclusive right of "first negotiation"
             and the "first right of refusal" for the United States territory
             and Latin America under the following terms and conditions. With



<PAGE>   2


             respect to the right of first negotiation, EEI shall notify quepasa
             of any confirmed tours of Gloria throughout the term of said
             exclusive right. Upon written notification by EEI of a future
             confirmed tour, quepasa shall have 30 days from the date of first
             notification to present and furnish a sponsorship offer (including
             consideration) acceptable to EEI and Gloria, and EEI shall furnish
             quepasa with a response to their offer no later than 30 days from
             receipt of the offer. In the event, the proposed offer is rejected
             by either EEI, Gloria or both, quepasa's exclusive right of first
             negotiation for sponsoring that tour will cease to exist and be
             null and void thereafter. With respect to the first right of
             refusal, EEI and Gloria shall notify quepasa of its first
             acceptable third party offer for sponsoring a confirmed tour within
             30 days of EEI's receipt of the third party offer. EEI will furnish
             a written statement to quepasa of the material terms and conditions
             of the proposed sponsorship offer by the third party. EEI shall
             offer to enter into an agreement with quepasa containing the same
             material terms and conditions offered by the third party. If
             quepasa does not accept EEI's offer within seven business days
             after receipt, EEI may then enter into that proposed agreement with
             the same third party mentioned in EEI's notice and quepasa first
             right of refusal with respect to sponsoring that tour shall cease
             to exist and be null and void thereafter. Without limiting the
             generality of the foregoing, the term of quepasa's exclusive right
             of "first negotiation" and "first right of refusal" shall expire on
             December 31, 2001. Without limiting the generality of the
             foregoing, the rights granted to quepasa in this paragraph in no
             way bind Gloria into accepting and performing in a tour throughout
             the term of these rights.

         5.  The cash payment of $0.5 million required to be paid by quepasa on
             the day after the final concert tour performance referred to in
             Section 1.H. shall no longer be payable under any circumstances by
             quepasa.

         6.  Upon the signing of this letter, EEI will return the certificates
             representing 156,863 shares of quepasa's common stock issued to it
             upon the signing of the Agreement and referred to in Section 1.H.,
             and thereafter EEI will no longer be the owner of those shares.
             Quepasa shall thereafter have no obligation to satisfy the "put"
             option described in section 1.H. of the Agreement with respect to
             any shares of quepasa. The Registration Rights Agreement entered
             into between EEI and quepasa shall be deemed cancelled, null and
             void.

         7.  EEI agrees to use its best efforts to provide opportunities (the
             "Events") in connection with Gloria's bona fide professional
             commitments through December 31, 2000, subject to the reasonable,
             practical limitations inherent in the nature of the Events, in
             which quepasa will have a right of participation and in connection
             therewith Gloria would make an appearance for quepasa. The specific
             activities in connection with the Events would be mutually agreed
             in good faith between EEI and quepasa and may include the
             following: (i) a mutually agreed upon number of the seats (as
             similar as reasonably possible to the number and type of seats
             originally to be allocated to quepasa for the Tour 2000 concerts)
             in the audience section of the theater where Gloria's contemplated
             live concert will be performed and for all other performances by
             Gloria through December 31, 2000; provided, that quepasa may only
             use these seats in on-line contesting as



<PAGE>   3


             contemplated by the Agreement for seats that were to be allocated
             to quepasa for Tour 2000 concerts, and (ii) in the event Bongo
             Cuban Cafe has a grand opening, webcasting Bongo Cuban Cafe's grand
             opening event. Quepasa, in its sole discretion, may determine
             whether or not to proceed with on-line contesting and webcasting
             the aforementioned events, if and when they may occur; provided,
             that EEI will not make any on-line contesting, webcasting or other
             opportunities contemplated by this paragraph 7 available to any
             other party without quepasa's written consent. EEI or a third
             party, other than quepasa, shall be responsible for all reasonable
             expenses incurred by Gloria or EEI in connection with Gloria's
             participation in and promotion of the Events. Quepasa understands
             and agrees to be responsible for any and all expenses incurred by
             its contestants and other persons it engages, other than Gloria, in
             connection with their participation and promotion of the Events.

         8.  All of Gloria's advertising, branding and website obligations will
             be limited to the activities described in this amendment to the
             Agreement.

         9.  Quepasa may assign its rights under the Agreement only to another
             corporation owned, controlled or acquired by, or merged with,
             quepasa, subject to the following conditions: (i) the assignee will
             not be a competitor to EEI or Gloria nor an entity whose
             association with EEI or Gloria as a result of the Agreement would
             reasonably be expected to be harmful to EEI's or Gloria's
             professional or personal reputation; provided, however, that,
             notwithstanding clause (i), quepasa may assign its rights under the
             Agreement to the entities listed on the attached Addendum A; and
             (ii) if such assignment takes place, the assignee shall be
             responsible for all representations and warranties made in the
             Agreement and shall be subject to the same terms and conditions
             therein.

         Except as specifically amended hereby, the Agreement remains in full
force and effect.

         All press releases, trade releases or other public announcements with
respect to announcement of the cancellation of Tour 2000 and the transactions
contemplated herein and in the Agreement shall be jointly prepared by quepasa
and EEI. Except for the information contained in each mutually agreed press
release and except as required by law, including the disclosure requirements of
applicable securities laws, the terms of this amendment to the Agreement shall
not be disclosed to any other person without the consent of each of the parties
hereto; provided, if such disclosure is so required by law, the party producing
or directing the production of such information will use all reasonable efforts
to provide the other parties hereto with notice of such disclosure and a
reasonable opportunity to comment upon, limit or contest such disclosure.

         This amendment to the Agreement shall be construed and enforced in
accordance with the laws of the State of Arizona. If any portion of this
amendment to the Agreement is held to be invalid or unenforceable, the remainder
of this Agreement shall remain in full force and effect and shall be valid and
enforceable according to its terms.

         This amendment to the Agreement may be signed in multiple counterparts,
and when signed by all parties, all counterparts shall be considered as a single
document.


<PAGE>   4


         If the foregoing correctly sets forth our understanding please sign and
return a copy of this amendment to the Agreement to the undersigned.


                                              Very truly yours,



                                              quepasa.com, inc.



                                              /s/ Gary L. Trujillo
                                              ----------------------------------
                                              By:      Gary L. Trujillo
                                              Its:     Chairman/CEO



                                              Estefan Enterprises, Inc.



                                              /s/ Frank J. Amadeo
                                              ----------------------------------
                                              By:      Frank J. Amadeo
                                              Its:     President



                                              /s/ Gloria Estefan
                                              ----------------------------------
                                              Gloria Estefan