When you need setup a custom role follow this scheme:
1) Go to a “Users->User Role Editor” page;
2) Click “Add Role” button at the right toolbar;
3) Input role ID, role name, select a role from which to make a copy (if not selected, then ‘subscriber’ role is used as a base role by default), click “Add Role” button at the bottom of the dialog window.
New role will be added and selected for further editing.
In order to add new capabilities to this role follow these steps.