What is mgtracker.org and how this open tracker work?

Hello,

i added open tracker "http://mgtracker.org:6969/announce" into private torrent and it has "Working" status and shows peers + downloads data.

So i wanted to ask what is the mgtracker.org, i see no website for it.

When i create private or public torrent and share torrent file (or magnet?) with my friend, we both use above tracker URL in torrent, i will be able to seed to my friend thanks to it and via DHT?

mgtracker is running some software that receive some data from me as a seeder and when someone else send a request, it will then attempt to connect the peer with seeder? for free, without need to submit any "Add torrent" form on their website?