How to add image header to top of page

[tyee]

Thanks Chris
I tried that but it seems it was resized and centered. I would like the full horizontal width of my browser used for the image.
This is what I used -

#header {
position:relative;
height: 200px;
margin: 0 auto;
background: url(images/bee1260x129.jpg) no-repeat top left;
}

How can I get it to be full horiz width?

Thanks
Tony