First there are many torrenting clients you can use such as: utorrent, bitorrent, limewire, and vuze. Personally my favorite is utorrent because it is the lightest and most efficient. So you can go here http://www.utorrent.com/ and download the latest utorrent program. Now you don't need to use this at all until later. So utorrent will download torrent files from the internet. These torrent files can be found anywhere on the internet and consist of things like music and movies. So you can go to Google and type in anything then torrent and you can download the torrent and then open it with utorrent or any client you may have downloaded. There are some websites that have good databases of torrents such as http://isohunt.com/lite/ and http://thepiratebay.org/. After you open it with a torrent client it will download to your computer. You have to be very careful while doing this though because people can share anything like illegal music and movies and viruses. To avoid viruses always check the comments of a torrent to see if people give it good reviews and say that it is virus free. There you have it now you can download anything you want to your computer from the internet.
P.S. Disclaimer: I am not responsible for any illegal activity due to this tutorial.