OK - I'm now just using the one table, and the site is currently set up to allow access to all the admin pages if users have logged in.
So I guess I need to change that and have two rules to allow access to different pages depending on which group the logged in user belongs to.
I have added a new field (User_Level) populated with either Administrator or Editor for each user.
I assumed the next step was to create two Groups, using Web Assist > Security Assist > Manage Site Access > Access Groups Manager, but when I looked in there, I wasn't sure as I was expecting to be able to define two groups where my field User_Level = Administrator and User_Level = Editor. But its more like asking me to enter users manually?
Or can I just edit the rules directly or create new ones based on being logged in + User_Level = Administrator / Editor?