I have added an audio file for playback (background music), how do I edit it for live streaming in my playlist or Live view.

For Live view: 

On your Live View Global settings:

1 -  press the icon   

2 - choose from the dropdown menu your preferred audio file for playback.  The audio file will play back        uninterrupted in a continues loop.                                                                                                                                                               

For Playlist:

If you edit the the audio playback option in the playlist editor section, then your background music will run and the audio will restart every time with your defined camera sequence allocated settings.