ArrayList USStates = new ArrayList()    ;
            USStates.Add(new USState("Alabama", "AL"));
            USStates.Add(new USState("Washington", "WA"))  ; 
            USStates.Add(new USState("West Virginia", "WV"));
            USStates.Add(new USState("Wisconsin", "WI")) ;
            USStates.Add(new USState("Wyoming", "WY"));

            Combobox1.DataSource = USStates ;
            Combobox1.DisplayMember = "LongName"      ;
            Combobox1.ValueMember = "ShortName" ;

  USStates.Add(new USState("Wyoming111", "WY111"));