How can i become an affiliate and how it works? Help

How can i become an affiliate and how it works? Help

Hi, i was wondering on how to become an affiliate since, i am a seller but want to get too in to affiliate. What an affiliate must do and must not do? How it works? Does it takes time to be one? Thanks for your time.
Also, i was level 2 and have already completed all requirements and have been days i am level 1, can somebody explain me this issue too? thanks once more.