>>25141. Download and install qBittorent.
2. Click a magnet link on Nyaa.
3. Wow, that's all!
(Depending on how hard your country cracks down on pirates you might also want to set up a VPN and bind it to your torrent client, but that's more important for Hollywood movies than for anime. You can also get into the nitty-gritty with settings etc., but for basic stuff like this it isn't super relevant.)