Using the 1st crocodile clip, connect the second end of the crocodile clip onto based of the headphone jack. The base of your headphone jack is considered the ground so it is connected to the GND of the @boardname@.
Using the 2nd crocodile clip, connect the second end of the crocodile clip onto the tip of the headphone jack. The tip of your headphone jack feeds into the right speaker on the headphone. You connect from the @boardname@ pin 0 to the tip of the right side of your headphone. Use the tip of the headphone jack to play sounds.