A. Add the following markup in header.php file just before the line which looks like <div ="wrapper"> 
<div id="xtra-container">
	<div class="new-leftsidebar">
		// code for sidebar goes here
	</div><!-- .new-leftsidebar -->

B. Add the following markup in footer.php file just after the line which looks like </div><!-- #wrapper -->
	<div class="new-rightsidebar">
		// code for sidebar goes here
	</div><!-- .new-rightsidebar -->
</di><!-- #xtra-container -->

C. Add the following to your style.css file:

#xtra-container {
	clear: both;
	overflow: hidden;
	padding: 0;
	position: relative;
	width: 1700px;
}
.new-leftsidebar {
	float: left;
	position: fixed;
	top: 0;
	width: 200px;
}
.new-rightsidebar {
	float: right;
	position: fixed;
	top: 0;
	width: 200px;
}