First of all you need a torrent program - I use
BitComet - then you need to go to a torrent site where there is a list of available torrents or a torrent search engine.
A good general site is
TorrentSpy For a good torrent search engine try
isohunt When you have found the file you want to download just hit download/open and BitComet will do the rest.
When setting up BitComet you need to open ports on your firewall/router to allow it to access the torrent system, there are numerous instructions on the help forum about how to do this. Go to
Portforward for instructions on specific routers.
Any more help you require just ask or PM me.