From this post on, everyone just assume that Paul is torrenting the newest Ubuntu release which is completely legal.
Mkay. Now I assume you have the torrent file. If you are looking for a program to open the torrent itself, there is bittorrent, utorrent, limewire, etc. What exactly do you need help with?
All joking aside:
1. Download your torrenting software
2. Install it
3. Open up TCP Port 6881 in your router as well as your windows/software firewall (or whichever your program specifies; usually is 6881)
4. Double-click your torrent file
It should start automatically. You usually get options like how much bandwidth to dedicate for upload and download. You can also pause the download and resume it at any later time.
I find that torrent downloads are kinda... "weird." They start really slow and take forever to get up to speed, and sometimes they don't even use your maximum bandwidth for whatever reason. They're good for downloading things on release date, though, such as Linux distros. FTPing the download on release day always sucks.