FancyZoom is a nice image lightbox plugin. Here is the simplest way to use it.

First you should have a way to initialize it when DOM is loaded , here we use addDOMLoadEvent introduced in Compatible Javascript code addDOMLoadEvent . Its better than old IE's load event.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "">
<html xmlns="" xml:lang="en">
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script src='FancyZoom.js' type='text/javascript'></script>
<script src='FancyZoomHTML.js' type='text/javascript'></script>
<script src='addDOMLoadEvent.js' type='text/javascript'></script>
<div  style="width: 515px">
    <a href="pic.png">
      <img src="pic.png" alt="" width="515" height="190"></a>

Enjoy it!