I want to get mental help but don't know how because I am underage?

You need to tell an adult, maybe a school conseler or something and ask him/her to not tell your parents. I know it can be hard but i was in your situation last year and i know it sucks but i got help and now i dont feel that way anymore. Its not going to be easy, but trust me, people care about you and im certain they dont want to see you go through this