You will start by facing a doorway to the bedroom. Go inside this bedroom. Turn right and you will see an opening and a couple of steps going up. Go up those steps and turn left. Go up another set of steps. In front of you is a doorway. Go inside this doorway and stand behind the black armchair. Now turn to your left and you will see a large sliding door opening. Stand on the left side of that opening. Once you're facing the wall with a switch on it then you're done.