All you need to do is to visit the city or town clerk's office together with your fiance and apply for a marriage license. The cost is $35 (by a credit card or a money order), and you both need proofs of identity (unexpired passports, driver's licenses, other government issued picture IDs). If you live in New York City, you can start the application on-line at https://www.nyc.gov/portal/site/cityclerkformsonline, it will save you some time. But, even if you file the application on-line, you both have to be physically present at the clerk's office and sign the application. The license will be issued right away (but you cannot get married for 24 hours) and will be valid for 60 days. You cannot file the petition until you are married. You can - and should - consult an immigration attorney before you get married. Unless your fiance has a bad criminal record (or another reason why he is inadmissible to the U.S.), filing of a properly prepared petition/application package should not put him in danger of being deported.
Answered on Aug 08th, 2012 at 4:58 PM