Online Documentation for SQL Manager for SQL server
Defining user membership
The Member of tab of User Editor allows you to define user membership, i.e. to select the built-in database role(s) the user will belong to. The selected roles determine the tasks that can be performed through the user.
To select a role, you need to move it from the Available Roles list to the Selected Roles list. Use the buttons or drag-and-drop operations to move the roles from one list to another.