Ok, first you apparate to the closed off area that you can't get out of without apparating back to where you were. Then you use WL (wingardium leviosa) on the bungy cord that's tied to the tree limb. This will create a bouncy tree limb (which looks like a tree hand). Then you jump to the higher level in the foreground where there is a black rock on top of a silver lego rock. Hold down the screen over the silver rock which will charge your reducto spell then release the button and break the silver rock. I find that in some of the scenes where you have to focus the reducto spells, like on locks and statues, your character has to be situated just so, so that the charged orange circle will even show up. As long as you've got you wand set to reducto, and you know it should break, just keep moving around until it appears and you can break it. Anyway, after you break the silver rock, this should then make the black rock available to WL to the ground by the snake game. I think you have to have spectrespecs to see the other rock to put on the other block to play the snake game. Hope that was helpful.