ok, basically what you do is d/l and install some software to use torrents --- there's lots of different versions of these clients, but I use utorrent.
bitcomet, like that guy mentioned, is another, but I've never used it.
google around a little for info on the programs because some can install crapware on your comp --- I think there's one that's infamous for this, but I forget which.
another popular one would be azureus, but you need java installed for that.
once you get that program all set up you're ready to search out some torrent sites.
torrent sites are like phone books listing thousands of 'trackers' which your torrent program uses to d/l the file from others who have it already, or who are currently also d/l'ing it.
so, the tenyardtorrents site is just a listing of specific trackers people post for various nfl games.
one thing you might also want to google and install before you get involved in any of this is a program called peerguardian2 which supposedly screens out some ip addresses from d/l'ing files from you.
see, torrents are different from some other p2p because while you are d/l'ing, you are also uploading the same file to other people who can see your ip address.
so, if some organization wanted to find out who was stealing dane cook's hbo specials, they could just activate a torrent and see which ip addresses are uploading the file.
if you get all hot for torrents and try other sites, just be careful about checking file extensions and file sizes, and try to stick to reliable sites because people can post all kinds of files and name them anything.