I need help! i am a high school school student who is planning to attend College and be a Cardiac Surgon. help?

the only problem is i don't really don't know what happens after high school. how many do i have to study before going in the Medical fields. and what does it mean when someone say im a sopre is college and etc... can someone please help me, and explain me how college work and how credits are counted because i really don't know anything. THANK YOU