Add following code just below opening form tag in master page.
<asp:updateprogress runat="server" id="upMainProgress" xmlns:asp="#unknown">
<progresstemplate>
<div id="load" class="n1 loadingProcess">
</div>
<div id="visibleDiv" class="loadingProcess">
<img src="images/loading.gif" width="43">
height="44" alt="Please Wait..." class="loadingbg" />
<br />
<span style="color: #333;">Please Wait...</span>
</img></div>
</progresstemplate>
</asp:updateprogress>