how do you get into the ghost's box?
Spoiler
you have to give the ghost the chains and he will give you a key
where do you get the chains?
Spoiler
the metal pieces you found have to be given to the blacksmith and he will make you some chains (wait for the good chains) then give them to the ghost
where do you find the metal pieces?
the metal pieces are on the floor beside the door of the first upstairs room.