Documentation on 'OG Forum'

My problem is about module 'OG Forum'.
I want to built a forum that should have this tree (presentation here) :

Forum A (product A)
* Forum A1 (customer 1)
* Forum A2 (customer 2)
* Forum A3 (customer 3)

Forum B (product B)
* Forum A1 (customer 1)
* Forum A2 (customer 2)
* Forum A3 (customer 3)
...

But these forums should be read either by product or by customer.

Thanks for your help