Thank you for using OnSong! The easiest way to back up your OnSong library is to export a backup file. To do this, open the Share menu from the menubar by tapping on the box with an up-arrow icon. This is located directly next to the "Songs" button on the iPad, and on the far left at the bottom of the screen on an iPhone or iPod Touch.
This will give you options to Export, Email, Print and share wirelessly. Choose Export. This will provide a list of formats to export. Tap on the OnSong Backup option to place a checkmark. Next, tap on the folder icon on the bottom of the screen to choose iTunes File Sharing. Tap on the Export button at the top of the screen to export the file. This will save an OnSong backup file to a location on your device where it can be retrieved using iTunes.
Note: This saves the backup file to your device which is not a safe place if your device is lost, stolen or damaged. You need to retrieve the file and store it on your computer so it is in a safe place. To do this, open iTunes and connect your device to the computer with the cable included with your device. Open the device by choosing it on the screen and then click on file sharing. Click on OnSong to the left and on the right will appear files in OnSong. Save the backup file to your computer by selecting it and choosing the "Save to..." button at the bottom.
To restore this file, connect the device to iTunes and then add the backup file to this same area using the "Add..." button. Then open OnSong and go to the All Songs tab in the Songs menu. Tap on the "+" button and choose to Import from iTunes File Sharing. Choose the backup file from the list. You will be warned that your current OnSong library will be overridden. If you choose to restore, your backup will overwrite your OnSong library.
You can view a video tutorial on how to do this here: Transferring Libraries with iTunes File Sharing
Hope that helps!