Hi,
I love your idea, since I personally would like to visit Africa, perhaps work or volunteer there to help entrepreneurs.

I'd suggest writing up your marketing copy explaining various programs you offer, then just marketing to get people to sign up. (Sounds easier than it is, but you have to start somewhere.)

Also, here are a couple of profiled travel pros on Idea Cafe.
Perhaps you could offer your African opportunities to them to offer to their clients or do some other type of collaboration.

https://www.businessownersideacafe.com/business_people/show_category.php?category_id=29

Cyberhost at Idea CafeThe Fun Place for Serious Business(sm) ;-) ;-)