A secret passage can be found on the first floor. It is one of the statues. Press A and go through it. It will take you to a silver door on the fourth floor next to the Hospital Wing. There is another secret passage on the sixth floor. It is the Golden Statue furthest north in the hall. It will take you to the Dungeon. You can also go backwards through the passages.
In the dungeons, the gray gargoyle is a secret passage to the sixth floor.
Hint: Quidditch:
Look in the radar at the bottom right side of the screen. Once you have seen the Snitch in the radar, search for it in the match. Press A to speed up. Press it repeatedly. Once you have sighted it, press B repeatedly to make sure you get it.