in the archived documentation section of the security assist support page, there is a tutorial for "User Level Authentication". It was written for security assist 1, but the idea is the same.
On the login page, open the server behaviors panel (Window -> Server Behaviors). in the list, double click the Security Assist Authenticate User server behavior to edit it. On the 3rd step of the Authenticate User wizard, you can select columns from the user table to store in session variables, select the User Level column.
Now, create the access rules for the different levels. Go to Webassist -> Security Assist -> Manage Site Access -> Access Rules Manager.
you will need to create a new access rule for each user level. Set the condition to "Allow If". For the Value, Click the lightning bolt icon and select the user Level session variable. Set the Criteria to "=". For the Compare To option, enter the value that would be stored in the user level column for the user level you are creating the rule for.