1. Make a square that's 4x4 blocks.
2. Inside the square, fill it with trampolines.
3. Put a goomba in the BOTTOM LEFT CORNER OF TRAMPOLINES
4. Add a mushroom to goomba/piranha plant and make it big.(This should fill the inside of the square.)
5. Click play and see the results
If done correctly it should look like a goomba/piranha plant in the middle of 4 trampolines surrounded by a box 4 by 4 blocks.