The purpose of any fire extinguisher is to remove one of the four elements of the fire tetrahedron, and stop the fire. To do this, we us the PASS method.

Keep well back from the fire. Keep yourself between the fire and the exit.

1. Pull the pin on the fire extinguisher.
2. Aim the extinguisher nozzle at the base of the fire.
3. Squeeze the handle.
4. Sweep from side to side.

Be careful. Watch out for re-ignition.