Nook Glowlight Library not showing up in Calibre

Hello All,
I am new to Calibre. I have had a nook for years, but have been thinking about changing over to Kindle. At this point I am simply trying to load my Nook Glowlight library into the Calibre library. When I hit the device button at the top it shows I have zero books. I have hundreds of books, so I am not sure what is going on.
Any tips or advice on what I should do or a step that I may have missed?

Thanks!
SLM