How to use Calender Extender in AJAX

<link href="Css/Calender.css" rel="stylesheet" type="text/css" />

<asp:TextBox ID="txtCallBackConTime" runat="server" Width="89px"></asp:TextBox>
<asp:Image ID="imgCallBackConTime" runat="server" ImageUrl="images/Calendar_scheduleHS.png">
</asp:Image>


<cc1:CalendarExtender ID="ceCallBack" runat="server" CssClass="cal_Theme1" Format="MM/dd/yyyy"
PopupButtonID="imgCallBack" PopupPosition="BottomLeft" TargetControlID="txtCallBack">
</cc1:CalendarExtender>