A child may hit his brother out of anger whenever he feels like it. Thus, people must go beyond id to learn to be socially acceptable. This is where ego gomes into play. Ego intervenes between instinctual needs and external reality. For instance, a child's id might want to hit his brother, but ego is willing to put it off until after Mom and Dad are out of the room.
Superego is just a more developed ego.
A child's superego would say that it is wrong to hit the brother and stop the child from doing it. The oral stage occurs in infants by age one. According to Freud, babies put things in their mouths and suck to obtain gratification. I am disinclined to agree. A baby has a natural instinct to suckle in order to recieve nurishment from his mother's breast.