You can add multiple users to a user group and multiple groups to other groups. You can also add the same group multiple times with different permissions. In this case, if there are overlapping permissions (for example, two different permission sets that both assign permissions to reports), the most restrictive permission set takes precedence.
To apply security to a node on the Navigation Tree:
(Conditional) If you are applying security to a folder or data source connection, right-click the node and click Folder Properties > Permissions or Data Source Connection Properties > Permissions.
(Conditional) If you are applying security to a report or dashboard, right-click the node and click Report Permissions or Dashboard Permissions.
Click Add.
In the dialog box, choose a user group and then choose a permission set. Reporting Center enforces this permission set for the group you select. You can also modify or create new permission sets.
Click OK twice.