background-image
Background properties can be set for individual elements or as a global (default) property which will effect the entire contents of the page. If a background property is not specified, the browser will implement the default color scheme (which is rather dull), which will almost certainly not look the way you intended.

It should be noted that in some browsers the background color will be rendered before any images used for the background 'wallpaper' (such as a .gif file) are loaded. It is recommended you use a color that will fit well with the background image.

background-image

This property is used to specify the image to be used in the background. The default for this property is to have the image placed in the upper left corner of the window. The image will not be tiled or repeated in any way, and will be attached to the page, not the element.

background-image values

none

This is the default, and causes no background image to be displayed. Since it is the default, it is mostly used to over-ride a previous background-image statement.

url
URL stands for Uniform Resource Locator, and is used to specify the location of the image file to be used.

EXAMPLE:

p {background-image: url(logo.gif)}

This example will assign the image file 'logo.gif' to be the background image.