Gather you parts required for installation. This should include:
The rubber
The rim
Windex
Spray the inside of the rubber, and the outside of the rim.
Position your feet on either side of the wheel. Grab onto something sturdy with both hands. While holding onto something sturdy, jump squarely onto the wheel. (Note : A skateboard deck can make this process a lot easier by helping to evenly distribute the pressure)
If the rim does not seat the first time, repeat the steps. It does take some practice.
Toss the wheel into the air with a back spin and let hit the ground and bounce back to you. This will seat the inner bead of the rubber into the rim.
Install the rubber back on, and ride.