If this is a bona fide marriage (not solely for the purpose of assisting someone to get a green card), then you should establish first of all if your intended spouse is eligible for adjustment of status (green card). Because if not eligible, he/she will have to go back to Mexico to apply for a visa, and depending on his/her circumstances maybe denied and required a waiver (for example, if they have overstayed, or lived in USA illegally, etc).

Note: The above response is provided for legal information purposes only and should not be considered a legal advice; it doesn’t create an attorney-client relationship. For more information or to schedule a consultation, please visit http://www.law-visa-usa.com/contact_us.html

If you would like to request a confidential legal advice or schedule telephone or email consultation regarding your specific situation, please email me directly at Attorney @ law-visa-usa.com . Office Telephone line is 1-402-210-2040 (please EMAIL first to schedule a consultation appointment). I am an immigration attorney and work with clients from all States and globally. More information at http://www.law-visa-usa.com/.

It depends on how the Mexican citizen entered the United States.

You may find out about the basic process here:

http://www.msclaw.com/Green_Card_for_Spouse/Why_Choose_MSCandAssociates.html

However, I suggest contacting me for a free consultation to discuss the details of the case. This can be requested here:

http://www.msclaw.com/Consultation_Request.html

In addition to the response above, you should consider hiring an immigration lawyer to handle this process for you. So often when a client handles it themselves, costly mistakes are made. Usually it costs far more hire a lawyer to correct the errors, than to prepare and file for you. Good luck.