1. Copy/Cut the unfinished file to a flash drive.(to do this, right click on torrent in your torrent client and open containing folder and copy/cut file to the flash drive)
2. On the computer you are transferring it to, load the same torrent (the little .torrent file, mostly in kb) into the client (uTorrent) or simply download it again, but when doing so please make sure its exactly the same torrent you are downloading, this will load the trackers on the torrent file into the torrent client.
3. After the download starts in the uTorrent, stop it, now go to the download path of your uTorrent, by default it is mostly found in the download folder.(the folder or file shadow will be created in the path by then)
4. Copy or cut the incomplete file on your flash drive from the drive to the path in step 3.
5.Now go to the uTorrent and start the download again, it will do a file check before the file continue the download. incase you did everything right but still download is stuck, Right click the torrent in uTorrent and then select Force Re-Check
If it doesn't work, make sure you placed the incomplete file/files in the right directory or path and make sure you are using and loading the exact same torrent file you used to start the torrent on your other computer.
A working internet connection is also needed.