<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:ImageButton runat="Server" ID="img" ImageUrl="~/Images/Icon1.jpg" />
<cc1:CalendarExtender ID="CalendarExtender1" runat="server" TargetControlID="TextBox1" PopupButtonID="img"/>
</form>