I'm not sure exactly what you mean by "figure our Harry Potter's scar", but the scar certainly plays a role in the characterization of Harry Potter. As a child, Harry believes he received the scar in a car accident. Eventually, he learns the truth about his parents and the origin of his scar. Once he enters the wizarding world, everyone seems to notice his scar. Harry tries to hide his scar and his famous identity. He is often given far more attention than he would like. His scar and his fame are unwanted. The contrast between the fame and Harry's desire for a quiet life show us Harry's true nature.
In the later novels, Harry's scar takes on a much more important role. We begin to realize that this scar is more than a mark on the skin. Harry is connected to the Dark Lord by his scar. We begin to suspect that there might be a strange reason for some of the inconsistencies in Harry's character. Eventually we find that this scar is actually part of a very magical charm called a Horcrux. Again, we see Harry's true nature in the contrast between him and his scar. We also see his selfless and compassionate side as he goes to sacrifice himself for his friends. Without the scar, Harry's character might have turned out differently.