I'm pretty sure this is the wrong forum for this kind of question, but I'll answer your question anyhow
goto..
Admin Control Panel > Usergroups > Usergroup Manager > Add New Usergroup [fill out fields/info and remember usergroup id]
then
Admin Control Panel > Subscriptions > Add New Subscription [add info/prices etc..] >
The change Primary Usergroup to the one you added when your added a new usergroup.
next
Now you can setup permission for this usergroup in Forum Permissions