Press in on the sides of the battery and pull up to remove it. The battery is connected to the "On/Off" switch on the handle. When you press in on the sides of the battery you release the tabs that hold it in place.
Line up the arrow pointing down on the battery with the arrow pointing up on the battery charger and press the battery into the charger until it clicks into place.
Plug the battery charger into an electrical outlet. The red indicator light on the battery charger will turn on, indicating that the battery is charging.
Unplug the battery charger when the red indicator light turns off. Remove the battery from the charger by squeezing the sides of the battery and pulling up.