|You should be asking in the Linux forum.|
IMO, Ubuntu is NOT the best choice for a newb. Although it has been getting a huge push lately, there are much better choices available...Mint Linux for example. Mint is based on Ubuntu but is more user friendly & comes with a lot of additional software this is NOT included in Ubuntu.
Assuming you can configure your ToughBook to boot from a USB device & you have a big enough USB thumbdrive, use UNetbootin to create a bootable Ubuntu installation:
EDIT: I just looked up the specs for your Toughbook. Even if you max out the RAM at 320MB (64MB onboard + 256MB in RAM slot), it will not run Ubuntu well. I suggest you look for a more lightweight Linux distro such as Puppy or Damn Small Linux, IF you can figure out how to install them.