There are two ways to stop or slow down on in-line skates. Master both techniques before you take your skates out in public.
Heel Braking
1. Roll forward with moderate speed on your in-line skates.
2. Transfer the majority of your weight onto one skate (the one without the heel brake.)
3. Keep the other skate on the ground, but lift up on the toe. This causes the heel brake to rub on the ground and slow you down to a stop.
Dragging a Skate
1. Skate forward at a moderate speed.
2. Transfer the majority of your weight to one skate.
3. Lift up your other skate and hold it perpendicular to the skate you're riding on, almost heel to heel.
4. Drag the wheels of the skate you're not riding on to act as brake.
5. Push harder on the dragging wheels to slow down faster.