The following video shows a demonstration of thrusters:
To do a thruster, stand in an open space with your feet shoulder width apart, and lift a barbell up onto your shoulders. If you don’t have a barbell, you can use another (preferably non-breakable) object from around the house. This might be a broomstick, a bowling ball, or a small box. While holding the object in your hands and resting it on your chest, squat all the way down. All the way down means that the crease of your hip goes below the top of your knee. Keep your back slightly arched the entire time (for an example of what “slightly arched” means, look at your profile in a mirror when standing up straight. This natural arch is what you’ll want to maintain in nearly all lifts to protect your lower back from injury). Now, explode up from the bottom of your squat and propel the object in your hands up over your head. Lower the object back to its original position on your chest. That’s one thruster.