<?php
$title=urlencode('Title of Your iFrame Tab');
$url=urlencode('http://www.facebook.com/wordpressdesign');
$summary=urlencode('Custom message that summarizes what your tab is about, or just a simple message to tell people to check out your tab.');
$image=urlencode('http://www.yourdomain.com/images/share-thumbnail.jpg');
?>
<a onClick="window.open('http://www.facebook.com/sharer.php?s=100&p[title]=<?php echo $title;?>&p[summary]=<?php echo $summary;?>&p[url]=<?php echo $url; ?>&p[images][0]=<?php echo $image;?>','sharer','toolbar=0,status=0,width=548,height=325');" href="javascript: void(0)">Insert text or an image here.</a>
<a onClick="window.open('http://www.facebook.com/sharer.php?s=100&p[title]=Title+of+Your+iFrame+Tab&p[summary]=Custom+message+that+summarizes+what+your+tab+is+about%2C+or+just+a+simple+message+to+tell+people+to+check+out+your+tab.&p[url]=http%3A%2F%2Fwww.facebook.com%2Fwordpressdesign&p[images][0]=http%3A%2F%2Fwww.yourdomain.com%2Fimages%2Fshare-thumbnail.jpg','sharer','toolbar=0,status=0,width=548,height=325');" href="javascript: void(0)">Insert text or an image here.</a>