probably because there is no single or simple answer… everyone sets up and manages their forum differently… easiest way is to look around the admin at the different panels… dont hesitate to ask any specific questions you might have…

you can add new admins on forum – admins – manage admins… you can give them all admin capabilities or just some… the capabilities control which admin panels they can access… admins can do anything on the front end…

have you visited the codex? namely http://codex.simple-press.com/codex/getting-started/ which will help you get started setting up your forum and control access to it… other topics including a faq on the codex too… we are still populating some areas though…

also one of our users whipped up an owners manual… give it a try: http://ernohannink.com/membership-program-with-a-forum-wordpress-and-simplepress/

and as I said, dont hesitate to ask question…