As long as your spouse entered the US lawfully and can prove that lawful entry, he will be eligible for adjustment of status to permanent residence within the US.  The necessary forms can be obtained from USCIS or their websiite, www.uscis.gov.  Please note, however, that it is not just the forms but also the supporting documentation that has to be gathered and assembled to be submitted to the USCIS.  If you are not sure of what to submit or how, you might want to consult with an immigration attorney.