how do I upgrade to OS X Lion 10.7 from a 10.6.8

https://discussions.apple.com/docs/DOC-2465

Before purchasing, make sure your system meets the minimum requirements which can be found here:

http://www.apple.com/macosx/specs.html

If your system meets or exceeds the minumum requirements, purchase and download the "Mac OS Lion" installer from the Mac App Store.

Once downloaded, the easiest thing you can do is run the installer and follow the instructions.