You are standing at the entrance of the door, facing towards the wall with a portraits hanged on it, turn left, you can see a staircase, walk to the staircase and stand on the first step of the staircase. Turn left, climb the step and walk straight, turn left, in-front of you there is a narrow path, walk straight in the narrow path and stand in-front of the open door which is on your right, that's your end point.