You can start by going through the docs of popular open source bit-torrent clients like qBittorrent (https://github.com/qbittorrent/qBittorrent https://github.c

You can start by going through the docs of popular open source bit-torrent clients like qBittorrent (https://github.com/qbittorrent/qBittorrent https://github.com/qbittorrent/qBittorrent) or Transmission (https://github.com/transmission/transmission https://github.com/transmission/transmission). Join the respective IRCs on freenode, observe the chats and ask specific questions when you don't understand something and Google can't give you good answers.