you have to get to the indicated spot. To control your truck you can select from using the device's gyroscope or the onscreen arrows. Plus you'll see the different buttons to change gears, turn your lights on, or adjust the trailers.
At the top of the screen you'll also see a map of the route to follow to get each truck to its destination. Plus you have to be careful with the raw material, as if you hit a lot of bumps the quality of your delivery will be reduced. When you finish each delivery you get rewards that give you the option to collect new trucks.
Through the Heavy Truck Simulator you can have fun driving various large vehicles through all sorts of levels. That said, the large number of ads really hurts the game experience here.