It depends on what userpermissions you are talking about. A lot of that is figured out in the php script for use in the template but it depends on exactly what is needed in the page. You can easily see if a user is a member of a usergroup like this:
HTML Code:
<if condition="is_member_of($bbuserinfo, 5, 6, 7)">
Stuff just for those that are members of usergroup 5,6, or 7
</if>