Make an appointment with the embassy through its website. New or replacement passports are only issued by appointment, according to the U.S. Diplomatic Mission to Nigeria. Appointments are issued in blocks, so you may have to wait up to 2.5 hours depending on how many other people are applying for a passport.
Fill out form DS-11 for a first-time adult passport or DS-82 for an adult renewal passport. If your passport was stolen, you will need to fill out DS-11 and DSP-64, applicable identification and provide a copy of the police report you made at the time of the theft. Forms are available at the State Department website.
Bring your completed form and all required forms of identification, your passport photos and the applicable fees (ranging up to $135 as of 2011) to your appointment. If the passport is for a child, the child needs to be present for the application process as well.