You, the U.S. citizen sponsor, must file Form I-129F, Petition for Alien Fiancé(e), with the USCIS office that serves the area where you live. See Direct Filing Addresses for Form I-129F, Petition for Alien Fiancé(e) for information on where to file the petition. Further information is available on the USCIS website under Fiancé(e) Visas. Note: Form I-129F cannot be filed at a U.S. Embassy, Consulate, or USCIS office abroad.
After USCIS approves the petition, it is sent to the National Visa Center (NVC). The NVC will give you a case number, and send your petition to the U.S. Embassy or Consulate where your fiancé(e) lives.