Dub, don't download the standard bit torrent client. Its shit. Use the ABC client which you download from here
http://pingpong-abc.sourceforge.net/
I've tried a few and this is by quite a considerable margin the best client I've tried.
I'm so gonna get this made as a sticky. I really am....
Bit torrent is a way of allowing lots of users access to single files without a single resource getting hit really hard. Imagine I have a file that 10000 people want, if they were all to try to get it off my machine, you can imagine that it'd take a while. What bit torrent does is to divide the files up into small chunks, imagine the file as a series of dominos. When you start downloading the client uses whats called the tracker to find out who has what bits (dominos) of the file. It will then access all the machines that have the information you need to construct the file effectively spreading the load across all the people that have downloaded and are currently downloading the file. Instead of hitting 1 machine for the file, you can potentially hit loads of machines, if they have a small upload speed (your download speed) thats OK, lots of small uploads can combine into quite an effective download speed for you. The more people that are downloading/seeding the better with bit torrent, it effectively adds all their upload speed (bandwidth) together.
Obviously if nobody has all the bits that make up the file, then you cant download that file. People that have the file in full are called 'seeds' and when you get your file, you should continue to allow it to be downloaded or 'seed' the file for some time so other people can get it and to spread the load. I use the ABC clients ratio settings to give 100% of what I take. I suggest this is a minimum.
The reason I recommend the ABC client is that the standard Bit torrent will always max out your upload bandwidth instantly, thus rendering the machine nearly incapable of browsing. ABC allows you to set the upload speed in K per second. It also aggregates this across all your downloads, so if you have 5 downloads it will spread the max bandwidth across all the downloads, allowing you to download a number of things at once.
You tend to find that it starts slow and builds up. Never got 2Mb out of it yet, but had 200Ks for Farscape whole 2nd series. 7Gb in way less than a day.
As mentioned
www.suprnova.org is a gold mine of stuff.
www.uknova.com has loads of british TV
To download a file, you need to find the tracker for that file. Its appears as a standard web link, but clicking it will cause the bit torrent client to kick into action.
Finding the trackers isn't that hard, but there is no 'definitive' central resource of trackers, suprnova is a good one tho.