If you want to fill a reseed request then all you need to do is download the torrent file from the site. You then place your already downloaded files into the same directory structure that the torrent is trying to create in your download folder and then ideally do a re-check in your client. As long as the files match then you should start seeding. If there are any discrepancies though then you can't help. The files and structure must be a precise match.