<script src="../javascript/My97DatePicker/WdatePicker.js" type="text/javascript"></script>  

<script>

    function selectMonth() {

        WdatePicker({ dateFmt: 'yyyy-MM', isShowToday: false, isShowClear: false });

    }

</script>  

<input id="starttime" type="text" style="width: 70px;" runat="server" onfocus="selectMonth()" />