using kodakgallery.com to print

Hello,

I have a powerbook g4 and am running tiger on it. I do a lotof photo editing through photoshop, then I like to upload my photos to kodakgallery.com and have them so the printing. However, my prints always come back looking a bit different than what was on my screen.

First of all, how do I ensure that the photos I edit in photoshop CS will display the same colors once I put them on the web and secondly, how can I make sure the the printed image will be the same as well?

thanks