you can open that? i tried going to it with a key but it didnt seem to open
It only opens once you find the ending cutscene. If you make your way to the right you'll eventually run into a room that is full of desks and a fire. After that you'll need to travel up and find the ghosts up there. There's a video walkthrough on my youtube channel just in case. It goes through everything except for the second outside area.