Read a good tutorial on CSS Shorthand properties : http://www.dustindiaz.com/css-shorthand/

Background shorthand code :

<style type="text/css">
div#id_name { background:red url(image_url.jpg) repeat-x top left scroll; }
</style>

<div id="id_name">
My Div have a good background image
</div>

The default background properties of a DIV :

#id
{
background-color: transparent;
background-image: none;
background-repeat: repeat;
background-position: top left;
background-attachment: scroll;
}