Syncing my Folder containing all my ebooks

Calibre Noob here

I have a folder that I keep all of my ebooks in on my Windows 10 pc. When setting up Calibre the first time I pointed it at that folder to detect the books i currently have in that folder.
I am going through about 10,000 ebooks on another hard drive that i have. I am moving the books that i want, to the folder that Calibre uses for my Calibre library but when i move books to that folder, how do get Calibre to recognize that i added books to that folder and then sync this folder to Calibre so that all the books in the folder appear in Calibre?
Thanks