I good example that’s completely legal is Linux distributions. They are licensed in a way that lets you share the file with other people so there is no risk of illegal activity.

You need torrent software installed that can speak the language of the torrenting protocol. Examples would be QBitTorrent, Transmission, and uTorrent, but there are others as well.

For the general process, you would download and install torrenting software, then you would go to a page that has torrent files (like this Ubuntu page), save the .torrent file and then from the software open that file, this will begin the download. Once it’s done, you have a full copy of the files on your computer.

The only thing unique about torrents is that you are downloading parts of the file from a bunch of other people that have a copy, instead of downloading the whole file from just one single server.