how do i apply for usa green card

Short answer

To apply for an Employment-Based Green Card (EB-2/EB-3) from Nigeria to the United States, you need a job offer from a U.S. employer and an approved labor certification. Submit Form I-140 (Immigrant Petition for Alien Worker) and Form I-485 (Application to Register Permanent Residence). Fees vary, typically around $700 for I-140 and $1,225 for I-485. Processing can take several months to years. Verify current rules on official government or embassy sites as requirements change.