On my PC I use Azureus (
http://azureus.sourceforge.net) and Tomato Torrent (google it) on my Mac. Basically you download the .torrent file and open it with your said Bittorent program. The .torrent file holds all the information about the tracker and so forth. Then it starts downloading pieces of the file and uploading at the same time. So if you have a bandwidth quota, monitor both sides although it almost defeats the purpose of Bittorrent since it's a distributed system. Enough mumbo jumbo.