This is pretty simple compared to jquery. Since we need refer a dll only. we dont want any script for this. we just include that reference into our website.

Please have a look at the coding.......

<asp:TextBox runat="server" ID="txtSearch"></asp:TextBox>
<ajaxToolkit:TextBoxWatermarkExtender ID="twSearch" runat="server" TargetControlID="txtSearch"
WatermarkText="Search Products..." />
<span class="search_button">
<asp:ImageButton ID="butSearch1" runat="server" ImageAlign="Right" OnClick="butSearch1_Click"
Height="30px" />
</span>