@mikay, the way it generally works is that you're proposed for membership by one or more of the senior Sndbox "Fellows" who has followed your content for a while and sees it as fitting into the incubator's mission. Then you would be invited to apply. The next "class" start rotation in July.

A good start would be to follow @sndbox just to keep up with their projects. I know several members of the Nigerian Steemit community are members.