如何将DataGrid.Columns与comboBox一起使用

its complicated becasue im doing copy list by the object UserX.. I have users list and i want to display them in table. I need that in the Role column the default value of the comboBox will be the user's current role, and I need option to change this role by using ComboBox and I dont know how ( the possible roles are: Administrator, Manager and Employee)its complicated becasue im doing copy list by t