Hi,
The website you provided have a white background defined (on the body element) and a background image containing a gradient defined here:
http://www.mofa.gov.sa/MOFADesign/MOFA-Images/Bg_Html.jpg[
^].
This background-image is 1px wide and is defined as repeat-x, so it will repeat itself horizontally.
This is the safe way to get it working on all browsers including IE6 / IE7. If you only want to support newer browsers, I would use CSS3 gradient definitions.
Here is a generator for such gradients (containing also a 'hack' for IE6+):
http://www.colorzilla.com/gradient-editor/[
^]
Here you can see how this is used:
http://jsfiddle.net/zhQAw/1/[
^]
Hope this helps.
Best regards and happy coding,
Chris