What are the best ways to hurt people there's this dchebg at school and he always insults me and picks on me I usually don't fight much but I want to show him not to mess with me once and for all?

Martial Arts are not for hurting people. The martial arts build discipline and skills to defend yourself if attacked. You must get your parents and teachers involved in any bully situation. I suggest you look at taking martial arts to learn how to handle a bully situation. It will give you options and confidence that you can handle a situation without hurting someone. If it comes to someone attacking you then you will know how to handle it.