I would first recommend you have the right version downloaded properly. I made the mistake of downloading a server version, which didn't work on my desktop, so make sure the version is appropriate for the computer. Next you'll need to burn the image file to disc, and if you don't have burning software you'll be sure to find something at download.com. Then burn the disc and boot from the CD for the live environment to launch, and install.
I need to know how to download ubuntu and put it on a cd, because ive tried twice from ubuntu.com and tried putting it on my desktop and the cd was black so can anyone help me?