So cool that you are interested in chemistry! A doctoral degree follows a bachelor's degree so your first step would be graduating from college with a chemistry, or closely related, major. It would be great to get some chemistry research experience while in college too. In your senior year of college, you would apply to graduate school with the intent to pursue a PhD in chemistry. Probably the chemistry faculty at your college would help you with this application process. Once you are in a graduate program, typically you take classes for 1-2 years and then transition into full-time research working on experiments for your doctoral thesis. All in all a doctoral degree can take 4-6 years, a lot depends on your progress in the research portion. I hope that helps and good luck!