Please help with lack of self confidence for my son around the us cool kids?

Empower him: What makes the other kids cooler than him? Nothing really...One of the best tools i know is a success journal. Every night write 3-5 things that were successes that day. Only successes. They can be small items. And when he feels badly or needs a boost read about the successes. Help him be happy with his gifts and skills because he is cool in his own right! he needs help seeing it.