Thank you for writing back with that information. Since you are using the DropBox software / app in your Mac, then you need to check and know the location of your DropBox folder.
Please open your Finder and in the left panel, under Favorites, you shall see your DropBox folder there. Open that folder, and everything you have in it is being synced to your DropBox account in the cloud.
So your best option in solving your problem with your folders in your desktop is to actually MOVE (copy and paste) them to your DropBox folder. Once you moved them there, Dropbox will then upload them to your account in the cloud. When you need to open those files for editing, just open your Dropbox folder again, locate and open the files for editing. After editing, save your changes and Dropbox will again sync the changed files to your dropbox account.
I hope that helped.
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