You can do this using with jQuery UI dialog, you can download JQuery ui from here Download JQueryUI
Include these scripts first inside <head> tag
<link href="css/smoothness/jquery-ui-1.9.0.custom.css" rel="stylesheet">
<script language="javascript" type="text/javascript" src="jquery-1.8.2.js"></script>
<script src="js/jquery-ui-1.9.0.custom.js"></script>
JQuery code
<script language="javascript" type="text/javascript">
$(document).ready(function() {
$('#trigger').click(function(){
$("#dialog").dialog();
});
});
</script>
HTML code within <body> tag. Use an iframe to load the pdf file inside
<a href="#" id="trigger">this link</a>
<div id="dialog" style="display:none">
<div>
<iframe src="yourpdffile.pdf"></iframe>
</div>
</div>
