To upload files, simply drag and drop them from your desktop to the file view. You should see a green outline around the file view when you can drop them to upload. Since the file view is only visible in the File and Edit views, you won’t be able to upload while viewing Review Links, Publishing, or Workspace Settings.
Uploads continue even when you switch views, and the multi-part uploader used will ensure that chunks can be retried after errors. You can also drag and drop uploads within the upload queue to reorder them.
To download files, you can right click them and select “Download”.