what to do if a pakistani wants to marry an American and relocate in America

The first thing that I want to say with regard to your questions is that (generally) nationality and citizenship have little, if anything, to do with how to immigrate to the United States (the Diversity Lottery being a noted exception). Thankfully, our laws for immigrating as the spouse of a US Citizen do not discriminate based on where you were born or what country you are a citizen of. Having said that, in order to answer your question, an immigration attorney would have to know a few things: 1. Is the "Pakistani" in the U.S. or outside of the U.S.? 2. If in the U.S., did the person enter lawfully (i.e. have his/her passport stamped at the airport or land entry by an immigration officer and he/she was allowed to enter the U.S.? If he/she entered in a status other than C, D or K and is still here, then he/she can apply for adjust of status based on marriage to a US Citizen. There are numerous resources on the USCIS webpage regarding how to file such a case on your own:  http://www.uscis.gov/portal/site/uscis/menuitem.eb1d4c2a3e5b9ac89243c6a7543f6d1a/?vgnextoid=9c8aa6c515083210VgnVCM100000082ca60aRCRD&vgnextchannel=9c8aa6c515083210VgnVCM100000082ca60aRCRD  http://www.uscis.gov/portal/site/uscis/menuitem.eb1d4c2a3e5b9ac89243c6a7543f6d1a/?vgnextoid=32d80a5659083210VgnVCM100000082ca60aRCRD&vgnextchannel=32d80a5659083210VgnVCM100000082ca60aRCRD However, you may also want the assistance of an immigration practitioner to be sure to screen that you are eligible for adjustment of status. Marriage alone does not guarantee your ability to be granted Permanent Resident Status. One must show that he/she is not ineligible due to any number of factors, including, health, criminal history, immigration history, security reasons, etc.