Problem with javascript/css tabs

Hey, I am trying to incorporate some tabs on to my webpage, without actually having a new page for each tab. But rather an 'anchor', so that I can easily swtich between the two or more tabs.

I've been trying to follow the tutorial at:
http://phrogz.net/JS/Tabtastic/index.html

but it doesnt seem to be working.

I've copied the markup code:

<ul class="tabset_tabs">
   <li><a href="#tab1" class="active">Tab 1</a></li>
   <li><a href="#tab2">Tab 2</a></li>
   <li><a href="#tab3">Tab 3</a></li>
</ul>

<div id="tab1" class="tabset_content">
   <h2 class="tabset_label">Tab 1</h2>
   Tab 1 Content
</div>

<div id="tab2" class="tabset_content">
   <h2 class="tabset_label">Tab 2</h2>
   Tab 2 Content
</div>

<div id="tab3" class="tabset_content">
   <h2 class="tabset_label">Tab 3</h2>
   Tab 3 Content
</div>

copied the header files:
<script type="text/javascript" src="addclasskillclass.js"></script>
<script type="text/javascript" src="attachevent.js"></script>
<script type="text/javascript" src="addcss.js"></script>
<script type="text/javascript" src="tabtastic.js"></script>

and also copied the source files into my directory:tabtastic.css,tabtastic.js,AttachEvent.js, AddClassKillClass.js, AddCSS.js.

But I dont understand why it doesnt work.
Any help is much appreciated.
thanks