eryk -
To print on a CD you need two things - a printer that supports it (many inkjets will), and media with a printable surface (typically a white matte side).
My printer is an older Epson (Stylus Photo 960). It comes with a tray you put the CD (or DVD ) on, then slide the tray into the printer from the front. To print you simply move the "paper thickness" lever to the CD setting, then insert the tray. It comes with a program for creating the image, or you can create a template in your favorite editing software.
With printable CDs you can have a simple text only design, or a full photo on the front. I also make sure to put a CD or DVD logo so that I can tell the difference when looking at them later.
-Ryan