491030 add imeage header for site

I want put an image(960x150) as header for my site,right now there is logo and white blank on the top of my site, I want Replace it with the header, but I want these link on the top "Sign Up,Login,Help" Remains in the same place and the header in the background, and I want be able to change image of header from admin panel. I attached a screen-shot for more Explain. thank you... and have a nice Day!!