To play music throughout the slides in a presentation, follow these steps:
1. Click the slide where you want the music to start.
2. On the Insert menu, point to Movies and Sounds, and then click Sound from File.
3. Click the sound file that you want to use, and then click OK.
4. In the dialog box that appears, click Yes to play the sound automatically.
5. Right-click the sound that now appears on your slide, and then click Custom Animation.
6. In the Custom Animation task pane, right-click the media file on the list, click Effect Options, and then click the Effect tab.
7. Under Stop playing, specify the options that you want, and then click OK.
8. Close the Custom Animation task pane.
9. Right-click the sound, and then click Edit Sound Object.
10.Click to select the Loop until stopped check box, and then click OK.
11. Run the slideshow to verify the audio and then Upload your presentation on authorSTREAM (the embed audio WAV format will play fine in output).