From TMB Wiki
What is this bittorrent all about anyway? How do I get the files?
The idea behind bittorrent is the SHARING of files and while you download you also upload. From this you get a sharing ratio and we ask that you stay seeding the file after you have downloaded it until you have at least a ratio of 1. Your ratio is calculated from the amount of bytes you have uploaded divided by the amount you have downloaded. For example: you have downloaded 500MB and uploaded 250MB, your ratio is 0.5.
If you are new to bittorrent then you will be advised to have a look at The Bittorrent FAQ which explains how bit torrent works especially this section on the meaning of certain words. The Bittorrent Wiki is another very good site for bittorrent information.
For a bittorrent client we recommend using Azureus. A good alternative to Azureus is µTorrent, with a much smaller memory usage, albeit with slightly less functionality, so may suit those running less powerful computers.