Background Image

The background-image property specifies an image to use as the background of an element.

By default, the image is repeated so it covers the entire element.

The background image for a page can be set like this:

Example
body {background-image:url('paper.gif');}

Below is an example of a bad combination of text and background image. The text is almost not readable:

Example
body {background-image:url('bgdesert.jpg');}


Source: http://www.w3schools.com/css/css_background.asp