You can select any Folder within a Binder and drag/drop or browse for a file to save in that Folder. The drag/drop/browse feature is located on the left side of your home screen.
Simply drag and drop a file from your computer desktop or from the "My Computer" (Windows) or "Finder" (Mac) screen. Or click "Browse" to go directly to your Explorer/Finder screen.
The maximum document upload size is 20 GB.