If the paperwork you are referring to is the petition for divorce filed by your ex, she needs to have the divorce petition served on you by a process server or the marshal.  You don't pay anything to be served with the petition for divorce.  You will also need to file an answer (response) to the petition for divorce within the time set forth in the summons.  There is probably a court filing fee for filing your answer with the court.  You file it with the court with an attached proof of service and serve a copy of your answer by mail on your ex.  You can use a court form proof of service.  The proof of service verifies the date of mailing to your ex.  The date you sign the proof of service should be the same as the date of mailing and the same date you file your answer with the court.