iTunes filesharing is a way of viewing files stored in the documents area of your apps.
Foliobook uses this for two things
- transparent logo files
- transferring Foliobook backups on and off the iPad
However its a feature that many people don't know about, though its simple to use.
3. Now scroll down the apps panel, at the bottom you will find the Filesharing panes. Drag your logo.png files to the document area or use the ‘Add’ button.