[SOLVED] Image on each page - not just the center column?

I am wanting a unique image to go beyond the center column of each individual page - I am using the code below but the image does not extent behind the sidebar, header or footer area - I have done a lot of forum searching and still don't understand.
What I am using:

/* background changes for each individual page */
/*about us*/
body.page-id-24 td#middle {
background-image:url("http://www.floatingpetals.net/wp-content/themes/atahualpa/images/purpletulips990.jpg");
}

Can you help?
Thanks in advance