If you're using Microsoft Powerpoint, download the music file and save it to your computer. 1. On the Insert tab, select Audio, and then Audio on My PC. 2. In the file explorer, browse to the music file you want to use, and then select Insert. 3. With the audio icon selected on the slide, on the Playback tab, select Play in Background. You can use apps like Audacity to help you play multiple songs across multiple slides. You can find more tips and instructions from Microsoft, here.