Thanks again. Can I ask a couple more?

Firstly, what part does the torrent file play apart from letting me download? Is it needed on my machine so that data can be uploaded to another user?

Secondly, sometimes on the upload screen I get the message "Unable to upload: transfer interrupted", with the option to click on Remove whereupon the filename disappears. I may find that this has happened several times with the same file. Same question as before - is there something I should be doing?

TIA

M