Logical roles

Hi,
   I was checking membership in asp.net and I like the authorization and authentication features. I have an existing database and the roles there can be determined from the tables. For example: employees, supervisors, job managers, project managers .. etc. I can tell if a user is supervisor if he is listed as superivsor in the employee table or in some query, job manager from a different view or SP. They what I would like to do is built my pages inside folders named: employee, supervisors, job managers, project managers .. etc and restrict access (set rules) to those folders to the corresponding roles. What do i need to do in order to implement the roles and rules in asp.net without using the data structure that ships with asp.net?

 Thanks

 
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