// LOAD THE FIRST HREF OF THE MENU_TOP ANCHOR TAG INTO THE DIV ID CONTENT_AREA UPON THE DOM LOADING
$(document).ready(function(){
$('#content_area').load($('a.menu_top:first').attr('href'));
});
// WHEN ANY ANCHOR TAG WITH A CLASS NAME OF MENU_TOP IS CLICKED THE DIV ID CONTENT_AREA WILL BE LOADED WITH HREF OF THE ANCHOR TAG
<script type="text/javascript">
jQuery(function(){
$('a.menu_top').click(function() {
var href = $(this).attr('href');
$('#content_area').load(href);
return false;
});
});
</script>
//THIS HTML UL WILL CONTAIN THE PAGES TO BE LOADED IN - PHP SCRIPT FILES WITH ANY DYNAMIC CODE, OR TEXT, YOUD LIKE
<ul>
<li>
<a class="menu_top" href="first.php">FIRST</a> /
</li>
<li>
<a class="menu_top" href="last.php">LAST</a> /
</li>
</ul>
<div id="content_area"></div>
