using colorbox js without plugin

I’m trying to use colorbox in wordpress in the same way that the demos
are called on the colorbox website. The colorbox js file is getting
included in the page fine but I get an error when I click on a link.
Nothing happens and firebug says: $.data(this, colorbox) is undefined
on line 189 and 208.
I put this in my header.php:

<script>
                jQuery(document).ready(function($) {
                        $("a[rel='example1']").colorbox();
                });
        </script>

And the link code is:

<p><a href="...
2011/03/taziam-bio.png" rel="example1">Testing Lightbox</p>

My test page is at http://bit.ly/fy6THV and the link is at the top and
says “Testing Lightbox”.

I’m wanting to learn how to do this manually (w/out a plugin) so I can customize my site and learn more about jQuery and WordPress.

Thanks!