U.S. citizens can get permanent resident cards (green cards) for the non-U.S. citizens they want to marry. A U.S. citizen who wants to get married to a foreigner, can get that fiancé(e) a K-1 visa, a temporary non-immigrant visa. This visa will permit the fiancé(e) to enter into the U.S. and get married to the sponsoring U.S. citizen. This visa is meant for those who wish to marry in the U.S. K visas are issued with a validity period of 90 days and before those visas expire, the fiancé(e) visa holders must get married to the U.S. citizens who filed visa applications for them.
Once they get married, the non-U.S. citizen spouses of the U.S. citizens can apply for legal status. U.S. citizens who choose this method must first file Form I-129F, Petition for Alien Fiancé(e), for the fiancé(e)s abroad to get them K-1 non-immigrant visas (fiancé(e) visas) in the U.S. Once USCIS approves their petitions, it will forward the approved petitions to the National Visa Center (NVC).
The NVC will then forward the petitions to the overseas U.S. embassies or consulates. The beneficiaries will be invited to apply for fiancé(e) visas by the embassies or the consulates. They can then get K-1 visas and travel to the U.S. as non-immigrants. Once they get married, the non-US citizen spouses can file Form I-485, Application to Register Permanent Residence or to Adjust Status, and gain legal status in the U.S.
Another way U.S. citizens can help their fiancé(e)s get green cards is by getting married to them abroad. After they get married, they can file Form I-130, Petition for Alien Relative, for their non-U.S. citizen spouses who are abroad. The sponsoring U.S. citizens must file this form with USCIS where it will be reviewed and then be forwarded to the NVC. NVC will collect the required documents and forward the petitions to the U.S. embassies or consulates abroad. Visa interviews will be scheduled and the beneficiaries will be required to apply for immigrant visas. Those immigrant visas will permit them to travel to America as legal residents.