No, this is not one of those truck games, wherein you drive the truck. The truck here drives by itself and your job is just to grab all the garbage that you can get your hand. You need to fill the garbage truck with the garbage while the truck drives automatically.
While the truck is driving automatically, you will see a straight line that keeps swinging back and forth. That is how you can grab the thrash. You need to wait for the right moment when the line is pointing to the direction of the thrash. If you click the mouse button while it points to the thrash then you get the thrash.