Ok so you either are wanting to try out Ubuntu or you already have it installed and are learning your way around the OS perhaps you have a pretty good knowledge of it already. Doesn't matter. This is a great guide for anyone who is using Ubuntu.

It also covers both GNOME and KDE so you can probably use this for Kubuntu as well.  Goes through everything from install and setup to security and virtualization.

If you are serious about using Linux/Ubuntu then I would suggest you read this guide. 

http://commons.oreilly.com/wiki/index.php/Ubuntu_Hacks/Getting_Started