Instructions
Cast the Lumos spell, by tapping Harry with the DS stylus and then drawing a lightbulb around harry, to see the statues in the dark.
Tap the first statue with the DS stylus to bring Harry next to it. Tap it again to make him grab it then tap the direction you want him to push it.
Push the statue over the "eclipse" icon on the floor, which is the top right spot. Once in place, the statue will crumble to form a ghoul. Shoot the guard with your wand to defeat it and another statue will appear.
Drag the second statue to the "quarter moon" icon on the floor, which is directly to the right of where the statue appears. Defeat the ghoul that appears and the third statue will appear.
Drag the final statue onto the last floor icon, the "full moon" icon to the left, to make the last ghoul appear. Defeat it and the door to the Slytherin Common Room will open.