Carrying on bit torrent downloads

ok, this is starting to annoy me now! i'm downloading a few things from a friend using bit torrent and have the torrent file (takes up like 2kb) and when i double click it, the download starts fine. but when i turn off my computer at night, come back the next day and double click the file on my desktop, it doesn't resume the download, but starts again! is there any way i can get the downloads to carry on whenever i boot up my computer?