Adding 728x90 Adsense banner at top of header

[beggers]

I'm still using the original Revolution Magazine 3.0 and it's working great but I need to insert a 728x90 AdSense banner in the header. My attempts have failed so far, mostly because I'm confused by the shadow graphics around the header.

I'd need to insert a full width section directly after the code that displays the top edge graphic (with the shadow):



In terms of code I need a new section/division between this:

PHP Code:

<div id="top">
 <img src="<?php bloginfo('template_url'); ?>/images/top.gif" alt="Top" />
</div>

and this:

PHP Code:

<div id="header">
 <div class="headerleft">
  <a href="<?php echo get_settings('home'); ?>/"><img src="<?php bloginfo('template_url'); ?>/images/logo.gif" alt="<?php bloginfo('description'); ?>" /></a>
 </div>

In other words, it would be one long black-background section that would appear directly above and across the over the current headerleft and header right sections of the header, with the AdSense 728x90 code centered in the middle (and it would have the correct shadows on the edges).

Visually speaking, the banner would appear above the site logo and the newsfeed and comments RSS icons. It should just look like the header was expanded at the top to include a banner, without any separation.

Any help would be greatly appeciated. If you like to look at the site for reference, it is here. Thanks!