I'm not going to spend time talking about DMCA or legal considerations but instead focus on the "how to", not the "should you".How to download torrents
What to watch out for
Since torrent sites generally don't attract many advertisers for obvious reasons, expect to see plenty of adult ads when visiting them (adult sites will advertise anywhere there is high traffic). Also expect plenty of popups which you'll need to close and periodically refresh some torrent search pages to get past. It's also a good idea to set your Max upload speed (the speed you're going to let peers download copies of the pieces of the torrent your downloading "While you're downloading it" to a minimum. Throttling your max upload speed back to 1kb per second might not help others but it can improve your download speed and can be done directly in the settings of your Torrent Browser.
How to locate "good" torrents
Each site will display both Seeders and Leechers next to each torrent list showing how many people are sharing the torrent (Seeds) and how many people are downloading it (Peers). Torrents with a high number of seeds usually download relatively quick while torrents with a high number of peers usually are good quality torrents. Some sites offer only torrent file downloads (download and then open with torrent browser to download) while others have magnet links (link to open torrent directly in torrent browser). After your file is completely downloaded it's a good idea to delete the .torrent file (if you didn't use a magnet link) from your filesystem to ensure others are still able to use it/you as a peer.
If your mostly interested in downloading films then the next issue in your home entertainment setup will be getting your files to play on your TV instead of your PC. To do this either copy the video files to a USB stick to insert into your television (change source to USB to access) or install a media server on your PC like Plex. Which can then be used to organize your films and broadcast/transcode them to be viewable on a variety of devices such as a Playstation, Xbox, or Roku.