Measure out a piece of wax paper that is as long as your comb and 2 times as wide.
Hold the comb with the teeth pointing down and fold the wax paper around the comb to cover both sides.
Hold the paper lightly against the comb. Place the paper and comb lightly against your lips and say "Oooooooooo". You might need to try it a couple of times!
The wax paper will vibrate, making a buzzing sound with a pitch similar to the sound you're making. Keep trying until you get the hang of it. Try any song that you can hum!