Sarah:
Grumpy_Mike explained it well, I waited for your response... How you want to trigger it would help. Push button, motion/vibration detector, light sensor, water level? Possibilities are by your imagination.
Look at the blink sketch as an example. Your turning an led on, thus making the value HIGH(normal OFF state for the sound board). Then turn the led off by making the value LOW(this would be your trigger), wait a few miliseconds, then turn it back on.