(To start the game you will need to click the green flag with your mouse or screen). In order to play the game you are going to need a friend to help you play. For the red car you will need to press the "a" key to turn right and the "b" key to turn left. For the yellow car you will need to press the "right arrow" key to turn right and the "left arrow" key to turn left. (Keep in mind in order to play the game you will need a partner to help you play. Make sure not to touch the green grass). In order to get the booster you will need to complete one successful lap with the cars for the booster to show up, however if you touch an one of the enemies then you slow down. If you hit the booster first you will have the advantage of being faster than your opponent. Have fun and try making all the other levels!
Credit goes to the the video: How To Make Car Racing Game In Scratch | Scratch Tutorial and Multiple Levels in a Game: Programming in Scratch 2.0 and Scratch Tips - Create a Timer with Variables