Tap on the playlist you have created to display the menu
Tap Edit to open the editing screen.
When the edit screen opens, tap the “+” button in the upper right corner.
The list of audio files in the app will be displayed.
Tap the check mark to the right of the file you want to add to the playlist.
When you have finished adding to the playlist, click the “back button” in the upper left corner to return to the previous screen.
Confirm that the songs have been added to the playlist, and the creation of the playlist is complete!