How long would it take for me to major in Psychology and what course should i take in high school?

I'm 15 and hoping to major in Psychology, I would love to understand the human mind and I know that I may change my mind in the future but my being mature for my age I am sure that this is what I would like to do...if you have any information that would help me (example: college courses to take, college suggestions and or, high school courses to take) please help me peruse my dream with your information :) Thanks :)