Wilbur is trapped in the barn: move Charlotte's web to help him to bounce to go out. There's several available power-ups, with different effects; with one of them, Wilbur stays fixed to the web instead of bouncing. Once the barn is clean you have to hit the door to escape and go to the next level.
Arrow keys to move Charlotte's web horizontally (so Wilbur can bounce there); space bar to throw Wilbur. Also the space bar enables Wilbur to be launched from the web when he's stick at it.