There are a few different background properties:
h1 { background-image: url('http://website.com/img/background.jpg'); }
h1 { background-image: url('images/background.jpg'); }
h1 { background-color: green; }
background-repeat: repeat;
This repeats on both the X and Y axis, and will essentially tile the image across the entire background.
background-repeat: repeat-x;
This repeats the background on the X axis, or horizontally.
background-repeat: repeat-y;
This repeats the background on the Y axis, or vertically.
background-repeat: no-repeat;
This shows the image only once, without repeating.
background-position: top;
background-position: right;
background-position: bottom;
background-position: left;
background-position: center;
background-position: 50px 20%;
There's a quick way around background images, and you don't necessarily have to type out all of the above code to set up your background images the way you want them.
background: green url('images/background.jpg') top left no-repeat;