I've checked the documentation and searched but been unable to find an answer.

I'm using the built-in verion of NewBB, and I'm trying to do group based administration of the forums, rather than assigning permissions on a per-user basis.

It's for a guild website, I'd like 3 levels of access:

A category that anyone can read and registered users can post to.

A category that "guild members" can read and post to.

A category that "guild officers" can read and post to.

I've created the required groups in "modules/system/admin.php?fct=groups", and assigned users to those groups, but I can't find out how to say "This forum is restricted to group X"

Apologies if this is an answered FAQ

Edited..........Its working guess that I was too sleepy to figure it out.

Process: After you create the new group; give it "Module Access rights" and "Block Access Rights".

Then you can add members to the group from here "Edit Members of this Group" or do it from the Edit Users

Now you must go to the Fourm and give RIGHTS to your new group.