How to authorize login users using FreeRadius???

Hello friends, I am running pam_radius_auth.so client on one machine and freeRadius server on the other machine. Authentication is happening fine for the user accounts. I want to give certain privilege levels to each user on client machine. For example network_admin, security_admin, guest etc privilages. How can i configure these previlage leves for authorization on client and server side? Thanks & Regards, VIJAY S.