Back in the old days, when a file sharing service got found out by corporations and started sending nasty letters, people stopped using that service.
Too bad the torrenting generation never learned that lesson and now torrenting is just one big clusterfuck of "seekret club" sites and paying (VPNs) to pirate, which is laughable.
I don't know of a tutorial, but most tools have to have support for I2P built in, otherwise they won't work. A good torrent client that does is qBittorrent.
Browsing I2Ps network with HTTP happens over a SOCKS5 proxy, so if aria supports that, you can use it too. https://geti2p.net/ should have more information.