this instructable covers using 7.10 (gutsy gibbon) it should work with most Ubuntu distros though.
Step 1: Getting the required stuff
ok first you need to go to http://www.adobe.com then click the "get flash" icon on the right hand side of the page. It should automatically detect the fact that you are using Linux and give you the correct file types.
click download, and save to disk the tar.gz file you DON'T want the .rpm or YUM files.