first the benefits of bit torrent:
-download from multiple users
-generally good download speeds
-sharing is required from all users (no leeches!!!)
-no waiting in line for a download
-downloaded file errors are virtually non-existant
-files usually hit some bit torrent sites before they get to other p2p programs
First thing you'll need is bit torrent! Go here to get it. It's 100% free... Although you can make a donation if you'd like... After installing it, you pretty much leave it alone...
So how do you download stuff off of it? You download bit torrent files off of a site. The most popular is Suprnova.
Once you've installed bit torrent go to Suprnova and browse their site til you find a file that you'd like to download. When you find one, simply right-click on it and choose "save file as" then once the file is saved (its a very small file and shouldn't take more than a few seconds to dl on broadband) open it. You'll see teh Bit Torrent GUI pop up and it will be displayinga few things: the name of the file you're downloading, the percentage done, the download speed, and the upload speed.
If you don't want to share you're upload with anyone. Well then too damn bad. p2p is based around sharing and leechers are assholes...
When the download is finished the GUI will display something like "Download successful" or "Download complete".
Well thats my quick guide to bit torrent. Hope it helped you with any questions you might have had...