I want to make a private forum which is only accessible by a secondary user group

[flowermama]

Is this possible? I have my members set to all be in the "registered users" category. I want to have secondary user groups that I can add members to in order to give them access to specific private forums. It seems, though, that if I make it so that those in the primary group of "registered users" can't see the specific private forum, then even if I add them to a secondary user group that has has permissions to see and post in the specific private forum, they still can't access it. Is that how permissions work? . . . If they are denied access by a primary membergroup then even if they are part of a secondary membergroup which gives them permission for access, then they still can't access that forum?

I hope this makes sense. I am totally new to this and my board was SMF, and I'm really confused at the differences.

Basically, what I need to do is have private forums that I can give certain groups access to. How do I do that?