background-repeat:repeat; or append it to the single background 'shortcut' background:#888 url(images/whatever.png) repeat; just as you would for repeat-x, repeat-y or no-repeat. Though repeat on both dimensions is the default behavior...
The background image should automatically tile; if you set no value, the default of "background-repeat" is "repeat". If you have something that is stopping the tiling, you can set it manually to "background-repeat: repeat". The other values are no-repeat, repeat-x (repeats only horizontally) and repeat-y (repeats only vertically).
In your css write: body{ margin: 0; padding: 0; background:#ddd url(images/example.gif) repeat; } Code (markup):