Problem with an external file to Urban Grey Side Menu

[emonbusiness]

Hi everybody!
I’m pretty new in programming and I need some help. I like so much “Urban Grey Side Menu” (http://www.dynamicdrive.com/style/cs...side_menu/P20/ ) but I have one little problem: I want to put de HTML code into external file named “menus” (no matter extension: css, js, txt, html) and into HTML page to put just one line code to call the external file. It’s possible to do this? Pls help me!
Thanks an advance!

HTML code:

<div class="urbangreymenu">

<h3 class="headerbar">CSS Library</h3>
<ul>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/category/C1/">Horizontal CSS Menus</a></li>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/category/C2/">Vertical CSS Menus</a></li>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/category/C4/">Image CSS</a></li>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/category/C6/">Form CSS</a></li>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/category/C5/">DIVs and containers</a></li>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/category/C7/">Links & Buttons</a></li>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/category/C8/">Other</a></li>
<li><a href="http://www.dynamicdrive.com/style/csslibrary/all/">Browse All</a></li>
</ul>

<h3 class="headerbar">JavaScript Kit</h3>
<ul>
<li><a href="http://www.javascriptkit.com/cutpastejava.shtml" >Free JavaScripts</a></li>
<li><a href="http://www.javascriptkit.com/javatutors/">JavaScript tutorials</a></li>
<li><a href="http://www.javascriptkit.com/jsref/">JavaScript Reference</a></li>
<li><a href="http://www.javascriptkit.com/dhtmltutors/">DHTML & CSS</a></li>
<li><a href="http://www.javascriptkit.com/howto/">Web Design</a></li>
<li><a href="http://www.javascriptkit.com/java/">Free Java Applets</a></li>		
</ul>

</div>