Every level in Bad Piggies has a finish line and a grid. You've got to place the items you are given in the grid to make some kind of vehicle that will transport a green piggy to the finish line. Start by dragging out items onto the grid. In level 1, for example, we'll make a simple car by plopping down a few wooden boxes and attaching wheels to the bottom. You can't get going without a pig. Drag the little pig from the toolbox into the grid (preferably inside one of the boxes... so he doesn't fall out) and a 'Tick' button will appear. Press this to go. Now, gravity will take over. Your vehicle will start rolling down the hill, and will hopefully make it to the goal. Once you start getting more complicated tools, like bottle rockets, engines, motors, and balloons, you'll be presented with buttons throughout the journey. You can tap these at any time to use the items that are attached to your vehicle.