member can not see groups list...

Hi,

Multisite installation with bbpres + Buddypress (BDpress) activate for one subfolder site.
This installation will not have public forums or groups.
We want to have this structure:
-GROUPS
---Forums
------topics

So now I have:
- a common member (not moderator or admin).
- 3 groups , but this user can see only his own group.

How can I make possible that if a member is logged in, all groups can be seen tomake him able to ask to be part of it?

Thanks