How to display SharePoint 2010 processing animation?
This is not a huge deal. Putting in following code on your page will help.
<div style="position:absolute; z-index:1000;display:block;width:100%" id="divInProg" >
<table id="tblExPage" style="display:block" width="100%" >
<tr><td align="center">
<table width="75%" >
<tr>
<td align="center">
<div id="s4-simple-card" class="s4-simple-gearpage">
<div id="s4-simple-card-content">
<h1>
<img id="gearsImage" alt="This animation indicates the operation is in progress." src="/_layouts/images/gears_anv4.gif" style="width:24px; height:24px; font-size:0px;" align="absmiddle" />
Processing…
</div>
</td>
</tr>
</table>
</td>
</tr>
</table>
</div>
C# Solution:
If you need to do this using C# code then may be following link by Mano Mangaldas may help you.
Programmatically show processing screen ( Using SPLongOperation )