If you have a US fiance, that fiance can petition you for legal status in the United States. They will file the fiance petition and you will have an interview at the consulate in the country you’re at. Once that fiance petition is granted, you will have a visa to enter the United States. You must be married within a 90-day period and at that time after the marriage your now spouse can file for you. You do not obtain permanent resident status until after the marriage has taken place.