No iCloud icon in my prefs.

I don't have an iCloud icon in my system prefs. I am currently running Mac OS x 10.6.8 and have done a system update and it says it's current. I know I need a later system to get icloud and cannot figure out how to do this? If anyone could guide me as to how to do this that would be great! I've tried searching the app store as some have suggested, to update and for icloud with no luck! Any info would be great! Thanks!