Top spin is done for the cue ball to follow the object ball after hitting it. It is done by hitting the top part of the cue ball; it can be hit at the center of the top, top right, or top left depending on how you want the cue ball to follow. The amount of power matters in how much you want the cue ball to travel while spinning. The height in which you hit the cue ball at determines how much spin will be put on the ball, this means the higher = more spin,

lower = less spin.