Asp.net with ADirectory(for authorization)

[naija naija]

Hi,
I'm using asp.net to validate users against ADirectory(which i did)!
Now i would be Implementing Role-Based Security with GenericPrincipals
and Forms Authentication.Would i need to
have the Adirecory designed with roles in it?For example have roles with
description like Admin,Corporate,Users etc in the Active directory
before i can use
GenericPrincipals,IsinRole to identify the user etc.. for authorization
which means allowing or denying access to a particular resource, object,
etc. based on the individual roles in the Active Directory .
Thanks in advance and ideas are all welcomed!