If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Click Shuffle and start the game. Then drag the pieces into right position with your mouse. When you a done you will get a nice picture of Dakar Truck. You can choose one of four modes to play. Watch out on time, if it runs out you will lose. You can always disable the time and you can play relaxed.