You should still at least fix your doctype.
<!DOCTYPE html PUBLIC "-//w3c//DTD HTML 1.0 Strict//EN"
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
to make sure your future css etc don't get snagged by Quirks Mode.
Anyway, I think you should take desert image, and in your image editor, make it look semi-transparent (use your background colour and lower the opacity of the image above it in a new layer... then flatter and save). Set it as a background image on the body (or html) element.
Use the background css properties to set your desired settings... in this case, you'll want "fixed" for the position.
Double check that everything you have on the page is still readable with that background image behind it (even faded, it does reduce contrast somewhat).
As a side note, you may not want "Saddle" twice for your alt text. What does it mean if I'm listening to your page and I hear "saddle saddle"??? I'd consider leaving them alt="" since they are seemingly just decoration but in the HTML.
I didn't look further down the page.