The goal of each level is to collect enough coins to make Mr. Ravioli happy. You need to return to him with at least 3 coins for each pizza delivered. Luckily, your customers are nice people and always leave a tip so you end up getting 5 coins per delivery.
If you happen to collide with one of the baddies on the streets, you will lose a coin.
Be careful not to lose too many, as Mr. Ravioli will unhappy and you have to replay the stage...
Follow the arrow at the top of the screen to find your customers. When all pizzas have been delivered, head for the exit sign at your very right to finish the stage.