Thanks Andrew - that helps me understand how it works. I'm on PC. At first I thought maybe I would just set up my entire drive under the dropbox folder so as I am creating new files, folders, etc. they are automatically in the dropbox and will sync. But I feel like I'm too far into the game to do that! LOL! Plus there are often things I don't want to end up synced (like the 200 images I took of a single subject when I only need 1 final).
Right now, when I'm done working, I go to my folders, sort by date, and anything with the current date I drag over. I suppose this will work for the time being.