How do i watch my torrent after it is finished downloading?

What type of file is it?

Simply go to the download location and open it with your media player.

Are you serious?

Double click to your downloaded file can make play or go to his destination and play.

@DrTeeth
Not all people know how torrents work.
Why don't you try and help next time!?

Files downloaded via torrents are no different from any other file that you download any other way. The question was so basic and silly I honestly thought you were joking.