After high school, a usual amount of time is 10 years to be a full-fledged doctor. Here are the steps that you'll need to take:
1) College. When you graduate from high school, you will start by going to college to ultimately get a 4-year degree. You can start at a community college and transfer to a larger one later if you like! You can actually get any degree you like there, however you'll need to take a set of college classes that are together called "pre-med". Mostly this is a lot of biology, chemistry, and physics!
2) Medical School. After you graduate from college with your degree, you will take the MCAT (it's like the SATs) and go to a medical school! These can take 4 years as well, and usually the first 2 years will teach you a lot about all kinds of medicine in the classroom. In your second two years, you get to do what's called a "rotation" where you spend time with different doctors that work in different medical fields. Surgery is one of those fields, but you'll also get to see a bunch of other stuff like helping children or people sick with diseases. During those 2 years you'll decide which field you like the most (maybe surgery!) or you can decide that you want to be a general practitioner which is like your doctor you go to for checkups.
3) Residency. After you've graduated from medical school and you've decided on your speciality, you will get matched to a hospital where you can start helping people and can be called a doctor (although you're not done yet)! A residency is usually 3-years and acts like on-the-job training - you are actually helping patients but you're working with more experienced doctors that help you out. These doctors-in-training are called "residents".