It's not any different from doing in on a computer with Windows. Once you get the media created you can just put it in the clean machine and boot off of it. As long as the media was created correctly/successfully you will boot to an option to Try Kubuntu or Install Kubuntu, then you just go through the installer prompts. Be forewarned, there may be programs you're used to using that are either not compatible with Linux, don't work quite the same way under Linux, or are not as stable under Linux. Feel free to ask further questions about it. It seems like there are plenty of people who are willing to help.