What do I need to file for green card after marring a citizen

The answer will depend upon how you entered the United States. The forms that must be filed will vary depending upon whether you are eligible to seek adjustment of status or need to obtain an immigrant visa through consular processing. Additional work may be needed if you were ever in deportation removal proceedings. You can read more about adjustment of status at http://myattorneyusa.com/adjustment-of-immigration-status. You can also read about consular processing at http://myattorneyusa.com/family-immigration.