The boy kicking the soccer ball would represent how the net is at rest until the soccer ball hits it which is considered the unbalanced force.
Newton's Second Law Law of Mass and Acceleration
The girl in this image would represent the force being allied to the chair. The chair represents two things the mass is the weight of the chair, and the acceleration is the chair moving at a fast rate after not moving.
When the further ball to the left is pulled back and released and hits the three other balls the ball furthest to the right would fly back and then hit the other three balls. The first ball the had be pulled back would be the action, and the second ball would be the equal and opposite reaction.