Make sure the battery charger and the battery are compatible. Check the car owners manual for battery details.  Connect the red clamp to the positive terminal.  Connect the black clamp to the negative terminal.  Plug battery charger into 240 volt wall socket and turn on.  Turn battery charger on.  Check it is charging okay and not showing any warning lights or alarms.  When charging is complete, turn battery charger off.  Unplug 240 volt power cord from wall socket.  Disconnect black clamp from negative terminal.  Disconnect red clamp from positive terminal. It’s okay to charge your car’s battery while it’s still in the car and connected.