Saving a newly streamed torrent that I may have ruined?

[Chrysalis]

First, I have just joined your forum. I read the rules and searched to see if this topic had already been covered and can find nothing.

Let me also say that I am older then a lot of users with whom I've spoken over th past few years about matters regarding the computer and they always seem amazed when I don't realize that everything concerning computers is just common sense.
I don't agree.
That said, I used Transmission for the first time today to stream a torrent of some 90 items that took hours to complete. When finished, and with a Christmas morning zeal, I opened my Downloads and clicked on the Transmission icon. When nothing opened I simply clicked and dragged a folder named for the newly arrived data, placed beside the Transmission icon, & dragged it to my desktop and only then began to look into how to open the thing. It seems that I can't use Transmission to do so as it tells me that it has already been copied. If I try to open any of the items by dragging it to the Preview icon on the Dock, it does nothing.
Now as yet I haven't seen the pixel vultures circling and so wonder: can someone help or have I destroyed this file?

Thanks

[Chrysalis]

Thanks for you advice but I'm not making any headway with it.
I tried Finder-Preferences-Advanced and clicked on 'Show All filename extensions' and nothing happened. As well, 'Open With' (Preview) did nothing. And neither did double clicking on any of the items in the file.
God, I'm a idiot.

Any other suggestions, anyone?

Thanks