To view which role a user belongs to

1. From the Home page, choose Security    
2. Click on the Roles tab
3. Search for the role that you wish to view and select it in the grid
4. Click the Users in this Role tab

The users in this role will be listed, you can add and remove users from the role on this tab. See How to: Assign a user to a role and How to: Remove a user from a role for more information.