To help elaborate a bit (since this is a newbie board), calibration is the matching of colours on-screen to printer.
The most accurate and fuss-free way of doing calibration is to use hardware calibrators, e.g. Eye-One, Spyder. Do a quick search in this forum or Google through these names and there's plenty of information on them.
If you don't want to spend all that money, for the most basic calibration, use the Adobe Gamma tool to at least set the correct gamma and white point.
Do note that in the end for proper printer output you'll still need to get the (ICC) colour profile for your particular (photo) printer. Browse through your printer manufacturer's website for more info.