Valdus says:
nice, and how do you do that? I don't think I saw it in the new user guide.
1. When you're at the main Forum selection screen for your game, click Administrative Control Panel at the top right.
2. It should take you to a Subforums page. Go ahead and type in GM Screen, then click add. This should then display that forum name with three symbols to the left.
3. Click the "key" icon (this is permissions)
4. Under the groups section, it should say "Add permission for: " then the name of the game. Click Add.
5. Should bring up the permissions list with all things set to Inherit. Set them all to No, and that will make it private