The default ubuntu 14.10 is 1.1GB. It will not fit on a cd-rom. Must be a dvd-rom. For burning ISO use Imgburn. http://www.imgburn.com/
If you have a dvd drive and some blank dvd's then you can just use those.
You can grab the 32bit iso directly here:
http://releases.ubuntu.com/14.10/ubuntu-14.10-desktop-i386.iso
or from a torrent:
http://releases.ubuntu.com/14.10/ubuntu-14.10-desktop-i386.iso.torrent
Most BIOS do not mention support of bootable USB but often will anyway. You must specially prepare your USB drive though!
I use LiLi to make mine when on windows.
http://www.linuxliveusb.com
You can choose Ubuntu from the drop down menu and it will do the rest.including downloading the correct iso and check its md5 to be sure it is not corrupted.
Be sure to check the box that says "format key"
When you boot, dont press the BIOS button, but do press the boot selection button [what ever it is ono your machine]
They USB may be listed under HDD's instead of USB devices. This is the case with my computer and many others.