Wouldn’t it be simpler to find a theme you like with this already built in?
You can do a google search and find nav menus that work with javascript or css if you really want to.
you could make a menu within the header.php, just underneath the content div – eg:
<ul id="menu">
<li><a>" href="<?php bloginfo('url'); ?>">Home</a></li>
<li><a title="About" href="#link#">About</a></li>
<li><a title="Photos" href="#link#">Photos</a></li>
<li><a title="Links" href="#link#">Links</a></li>
<li><a title="music" href="#link#">Contact</a></li>
make some pages in Admin, and put the links there to match
then in your css, create #menu, add a hover tag, background, visited etc etc etc and you can have nice dynamic css made rollovers.
nice & easy