Since the original iPod, Apple has used a program called iTunes to manage your music and synchronize that with mobile devices. When the iPhone and iPad were released, this product was extended to not only synchronize music, but also video, books, and much more. App developers could also use this same capability to allow files to be transferred into a special location within an app using a function called iTunes File Sharing.
Note: If you are running a newer version of macOS Catalina or higher, you will want to read how to use file-sharing in macOS Catalina since iTunes has been split into multiple apps.
You can follow Apple's instructions for transferring files to your device on a Windows PC or transfer files on an older Mac which is comprised of these instructions:
- Plugin your device to your computer using the sync/charge cable.
- Open the iTunes application.
- Locate the icon that appears with a small iPad or iPhone icon inside and click to view details about the connected device.
- Click on the File Sharing tab at the top of the screen.
- Scroll down and then locate the OnSong app on the left side.
- Drag and drop files on the right side of the screen like you would a folder on your computer.
- Open OnSong on your device.
- Open the Songs Menu by tapping "Songs" in the Menubar.
- Select the Songs tab at the bottom and are viewing All Songs, or a selected book.
- Tap on the + icon to open the Add Songs Menu.
- Select iTunes File Sharing from under the Import section.
- Select the files you want to import and tap Import.