May I ask if you burned the ISO file to a CD or burned the 'disc image' to a cd. one just copys the iso file as a single file(which may have failed as it could have been just over the capacity of your CD which are normally 700M), the other to use an analogy 'expands' the iso file onto a CD creating a fully bootable disc.
I'll step back now and let young Mr Cyfr guide you through the joys of Ubuntu.(My preference would have been Knoppix(
www.knoppix.org ) or any other KDE based distro as its 'closer' to Windows than Gnome based ones (of which Ubuntu is one). One of the wonderful thing about Linux is that there is choice in nearly every single aspect of it, you try a few and see which ones suit the way your brain works, we are all different and what seems natural to one is awkward to another. I know Cyfr likes Gnome, I prefer KDE.[1]
Anyway good luck on your journey of discovery....
[1] GNOME - KDE are window managers , think of them as extreme 'themes' where you setup how your GUI desktop looks and behaves. Have a google for Gnome desktop images and KDE desktop images