Find the bricks in the levels; then buy them in the Hub area; then open your menu, choose extras, and choose to turn the bricks on or off. It's been awhile since I've played, but this is how it typically works in Lego games.

Don't get so worried. It's actually really, and I mean, really, simple. Just press start, go down one, press x, and then you'll see the cheats that you've bought. To activate one, just roll over the cheat, and press x. To de-activate it, just roll over it and press x again. Simple!!!!!!! Your welcome! :) :) :) I hope you understand this! And if you can't, then I'm sorry for you. :( :( I just have a weird habbit of explaining things in as much detail as possible. Once again, your welcome! :) :) :) :)