mazza, it is LIVE CD, that is you just put the CD in drive, make it first boot device then reboot. Your computer will now boot from Ubentu. In new version of ubentu, after booting, you can install the OS by clicking install icon in desktop.

I have one CD, but it got some problem with my display card, not able to boot with it.

Anyway i am not planing to use ubentu on my pc. I mainly use FreeBSD for testing and have a Fedora Core 3 installation that i rarely use.