Right now you're facing towards an opened door. Move towards that opened door. Now, slightly  turn left and walk towards the fireplace, which is in front of you. Now, turn right, you can see a staircase. Move towards the starting point of the staircase and turn right. Walk all the way up through the stairs. After you reach the end point of the staircase, take a few steps and stand at a point, where you can find an opened door on the left side and a portrait in front of you and that is the end point.