My friend Aman has written an excellent guide of how to download stuff using the latest in P2P i.e. torrents. Here are some of the important parts of the guide. The link to the article is at the end of the post.

Basics:
Firstly get a good client such as µtorrent or Azureus(Java), BitComet(C++) .Other Clients are not recommended!

The torrent file is not the file you aim to download, but a small file containing information where the bits of files are are located and information of trackers. Bittorrent isn’t linear though, it randomly sends and receives pieces from random users connected via the same torrent file.

Terminology:

• Leecher: That’s the guys that don’t have the complete file.
• Seeder: Those that now have the entire file, 100%, and therefore only function to upload to those that haven’t got the whole thing yet.
• Peers: All users connected to the same torrent. The more peers, the greater the speeds, providing there are enough seeders.
• Tracker: The centre when you start up the torrent. In short – it connects you to other users and is also the thing that sends you messages to your client.

Complete list of terminologies.

How to download:
Head over to your favourite Bit torrent website which mind you don’t host files but simply host the .torrent file.When you find a torrent file online, you download it to your computer. Its recommended to keep the actual .torrent-file on your hard disk, in case you need to restart it. Now open the .torrent file in your bit torrent client, and tell it the place you want to store it. It starts download the minute the tracker has picked up on you being amongst the peers. Most tracker needs AT LEAST a few minutes to pick up, so leave it alone for a while.

The stuff I have is very little and it would help you greatly if you read the complete guide: http://www.fudge.co.in/2007/06/01/torrenting-for-dummies/