How do I add sound to my game?

Anytime I add the .mp3 it says that the resource does not exist in the game. I can’t find a add audio anywhere.

To add audio:
In the events list, add an action. Select “play a sound” and you should be able to select a file from your computer.

If you’ve already done that. Go to project manager, then click on Resources. Do you see that mp3 file in your list of resources?