There is no jump button available for the game. You can jump based on your speed and the surface you cross. For example, try to gain speed then head to the edges, anything that can lift you up. You will automatically be thrown in the air where it's the perfect place to practice combos. This is the only way to jump in the game and in most of these stunt games. The jump button is available for games like Tony Hawk Pro Skater where you can launch yourself into the air by pressing a certain button on the keyboard.