How Can I Help My Kid Develop Better Social Skills?

My son is good at learning. But he is not willing to interact with other kids. He has just one friend. Hae all aways try to go waay from kids. At the school with teachers also he is quit. Teachers can not exactly understand him. whether is know or does not know the thing. But he is an intelligent boy. He scared to jump from height. To much concern about risk. He is just 6 years and 2 months old.