https://help.bittorrent.com/en/support/solutions/articles/29000039597-how-do-i-migrate-torrents-from-a-different-client-to-bittorrent-
If you're using a program other than uTorrent or BitTorrent, you'd be looking for import steps
Because of the way that uTorrent and BitTorrent store their incomplete files, there is no "export" that needs to be done from their side.