Positioning an extra wide image behind the menu bar

What an awesome theme and forum. Thank you!

I placed an image behind the menu bar. The image is wider than my container. I'm having trouble positioning the image and getting it to appear beyond the width of the container.

• Here's what I'm trying to accomplish:
• Here's how it looks so far: http://wgtdblog.com/
• Here's what I've inserted in CSS Inserts:

ul.rMenu,
div#menu1 {
background: none;
border: none;
background:url(http://www.wgtdblog.com/wp-content/t.../menu-bar3.png) !important;
}

I'm using Atahualpa 3.5.1 and WP 2.9.2. I would really appreciate your help. Thoughts?