White balance is the tone of daylight (or light) in the image. Your camera should have some 'preset' white balances such as "daylight", "cloudy", "shady", "fluorescent" (maybe tungsten), "incandescent", "flash" and then there's usually a setting for "custom" white balance where you use a grey or white card to set the white balance. Most cameras also have an "auto" white balance.
The problems in using the preset balances generally appear when you are dealing with more than one light source and they are both different (such as incandescent and fluorescent lights in the same room).
Try this:
http://www.betterdigitalonline.com/H...tebalance.html