Hi Marcy, The Ribbet library is a simple, flat collection of your photos and it’s not currently possible to arrange this into folders. There also isn’t currently a way to transfer photos from Picasa to Ribbet, although you can directly access all your Picasa photos and folders from the Library > Picasa, Google+ tab within Ribbet. You can also directly save back to Picasa from Ribbet.
For these reasons, if you need to organize your images into folders and you already have a collection setup within Picasa, you may be better off leaving them within Picasa and accessing them from Ribbet. You can bulk upload your photos to Picasa, and then head to Ribbet where they will be readily available for editing. Hope that helps.