On this tab, you can view all the Users assigned to a particular role, roles assigned to a user as well all security access details for a User assigned at a the Hierarchy level. This tab is a view only tab and you cannot create new details on this tab.

NOTE: Details for the Role's Users can be defined on the Setup > User Management > Shared Teams tab.

To assign a user to a Role,

1. In the Actions column corresponding to the required Role, click on the Manage Role User's icon. 
2. In the Manage Role Users dialog box, select one or more Users to be assigned to the select Role and click on the Save button.
3. The selected user is displayed in the User column corresponding to the selected Role.

___________________________________
Pre-requisite: Define Roles, Users.