Installed Digital Edition on the computer but it does not recognize the Nook HD when I plug it in and open Adobe....how can I transfer a book from computer to Nook if it doesn't recognize it....?

I have just installed Adobe Digital Edition on my computer.  I closed it and then plugged in the new Nook HD and opened the Digital Edition back up - it does NOT list the Nook in the left side so I cannot move the book to the NOok....how do I get this recognized so it works. ?