need a phph script for user management

I need a PHP script so that I can create users so that when they login, it gives them access to a certain area based on how I've set up their account. In other words, i would like the user management script to be able give them access to an area for their user name where I have certain users confugred as customers where they get access to a customer area, OR if I have them setup as a sales person, they gain access to my sales staff area. I have a script in place that authenticates their login but I need GUI interface where I can assign certain rights, customer or sales, to that user and after loggin in it redirects them to the customer or sales staff area. Is this possible and what free PHP script will do this?
Thanks!
Buster