You can submit your passport in person or by mail. If you are submitting in person, this is what you should do.
Proceed to VFS Global office at Lekki with your passport, the passport request letter, two passport photographs (one of the passport photograph should be stamped and signed by the photographer then your name and date of birth written on it). You should also fill form IMM008 and Additional Family Information Form ONLY if there has been a change in your family composition or marital status. If there is none, then there is no need filling out those two forms, just jump to the Height and Eye color chart. You will also pay a transmission fee of roughly N8200. I hope this helps. Do not hesitate to reach out if there is anything that is not clear to you.