Do you have an business partner or supplier in China who can send you an invitation letter issued by local Foreign Affairs Office? The visa rule for Nigerians are very strict, if you don't have the official invitation letter, you can't book an appointment first from the embassy.

my invitation is on d way,so how do i start processing d visa?

Prepare documents as what listed above for F visa applicaiton, with the invitation letter from China, you can make an appointment first to the Chinese embassy. And then, submit your application according to the date you were told. The general processing takes usually 1 or 2 weeks.