How to add a background image that sticks to the container

[solve]

Hi,

Does anyone know how to attach a background image so it always is in the same position compared to the container. Like this website here:

live.ripcurl.com/?portugal2011

The background has rough edges that sit next to the main content whatever the screen resolution.

Ive seen lots of sites like this recently.

Also what would be the best background image size for all browsers?

Thanks in advance

[ashimaathri]

I think they have tried to fit all the elements inside the background.
The width of each div is 970px whereas the background image is 1018px in width.
You can use Firebug or Chrome Developer Tools to check out the design of the sites you like.