Pick up the metal tool that came with your Heelys and turn over the Heelys shoe while it is off your foot.
Place the tool on the edge of the rubber piece near the back of the shoe and pry it up.
Pop the Heelys wheel into the place the rubber piece used to be. The wheel edges should be even and it should be able to spin easily in both directions.
Sit down on something sturdy and put on the shoe, tying the laces tightly so the shoe won't come off.
Repeat the steps for the other shoe.
Move yourself carefully to a smooth wood or concrete surface to ensure you won't trip while using the shoes.
Stand up carefully and place your dominant foot forward, the toe slightly angled up, so that your foot is completely resting on the wheel.
Place your non-dominant foot behind your dominant foot, and rest the toe of the non-dominant foot's shoe against the back of the dominant foot, balancing carefully on the wheels of both shoes.
Push off of something firm and you will glide across the hard surface.
Step the toe of your non-dominant foot down on the surface to completely stop after your movement slows, then push off again on your non-dominant foot, placing the toe of that foot back on the heel of the other foot. Your dominant foot should still be in front. Begin balancing on the wheel of the non-dominant foot as soon as you push off so you will go farther and faster.