To play the Mario coin mini-game, you will need at least one song file on the console that can be played in "Music". While in the "Music channel" on the Nintendo DSi, start a song, then instantly pause it. Look at the bottom screen's shoulder instruments. Scroll through until the "No sound" icon is displayed. Press Up repeatedly until the screen with Mario running appears. Press "Play", and use L and R to make Mario jump. Note: The shoulder button sounds need to be set to "None" so that the audio does not become distorted.
On the DSi Sound Channel, record a sound. Then, go to the box with four squares. On each of the squares there is either a parakeet, low harmony, trumpet, or electric fan. Click on one of them to alter the recorded sound according to the square you picked. If you click on one of the squares after it is already in use, it will change into a new sound. For example, if you are using the electric fan sound, it will change into a tunnel sound.