How do you get to big boos balcony?

If you are talking about Super Mario 64 ds, then as Mario, enter the mansion, go up the big stairs and go where the power flower box is right above the entrance. Go through the door next to it....and....um Bah! This is soo hard to explain! umm ya know where the two power flower blocks are? well go to the one in the room that has some books in it, AS MARIO get the power flower to float up to a secret room above the room that you WERE in..... then...... go through the door where you will see Luigis painting. DONT GO IN THERE UNLESS YOU DONT HAVE LUIGI YET and go to the big door up the 3-very-flat-stairs in order to enter the balcony. After you defeat the Big Boo, you can get the power flower block to float up to the roof. There are some items that you might enjoy. And if you dont understand me, watch YouTube....