Lightbox 2 Cita: Lightbox 2 uses the Prototype Framework and Scriptaculous Effects Library. You will need to include these three Javascript files in your header (in this order).
Código HTML:
<script type="text/javascript" src="js/prototype.js"></script>
<script type="text/javascript" src="js/scriptaculous.js?load=effects"></script>
<script type="text/javascript" src="js/lightbox.js"></script>