It is a broad question and to answer it properly you need to consult with an experienced immigration attorney. The advice will depend on your legal status in the US, the way you entered the US, whether you had prior criminal violations or deportations. This list is not all-inclusive. American immigration laws are very complex and each individual case is unique. I strongly suggest to seek advice with an attorney before commencing any action. Best of luck,
The forms you will need to file are an I-130 to establish the marital relationship, a G-325 (biodata) for the alien and for the US citizen, an I-765 for a work card, the I-485 for the green card, along with the I-864 affidavit of support. The alien will also need a medical exam from a CIS approved doctor. The alien may be able to file the I-131 to get a travel document if he has not been out of status for more than six months. These forms and the documents that support them (birth certificates, marriage certificated -- see the form instructions for more information) should be filed all together with the USCIS "lockbox" in Chicago.
Once your petition and applications are properly submitted, the alien is here legally pending adjustment of status. Following a fingerprint appointment, a final interview will be held to determine whether the marriage is real or not. If everything goes well, the green card is issued that day.