In this example I'm going to make a normal anchor open up a Modal dialog. Are you ready?
Within your php code tags enter the following:
<?php
JHTML::_('behavior.modal', 'a.modal-button');
?>
Add an anchor and the following to the anchor:
<a href="http://www.google.com/" class="modal-button" rel="{handler: 'iframe', size: {x: 725, y: 520}}">MyMooModal</a>
And that is all there is to it. You can specify ANY link and it will open in the Modal Dialog