It's not really that hard.
Just download one of the many clients you desire. JUST one.
I use http://www.utorrent.com/ but you can get the other if you prefer that, like ABC, old Bittorrent, Azureus, BitComet, w/e.
Then just open any *.torrent file. Your client should automatically do the rest. Of course the file must be seeded, or you won't be downloading any at all.