Now that I know where to access the server behaviours, life becomes a lot easier.
With regard to groups, I have used these before in ASP, and when a member logs in, a session variable is set holding the group he belongs to. This information is pulled from the database. When he tries to access the page, the page checks the session group variable to see if this group is allowed to enter the page and if it matches, lets him in or sends him elswhere.
In order to allow users to belong to groups, surely the group that a member belongs to must be stored in the database. If you have to tell SA which group each member belongs to, you could be typing for years. I have 28,000 members on my site. Apart from about 60 or so, which need to be individually grouped, the rest are automatically put into the default groups by the default value created by the MySQL database on registering.
How exactly does the group thing work?