Learn to code. You must have done a programming course in school. It shouldnt take you very long to learn php, django or rails. About your more general questio

Learn to code. You must have done a programming course in school. It shouldnt take you very long to learn php, django or rails. About your more general question "How do you deal with doubt?". The answer is that you ignore it and keep going. By definition an entrepreneur will always have doubt. He has to just keep working and getting feedback from his customers regardless of the doubt. Accept that you dont know what your doing but devise an experiment that will make things clearer and then go execute it and learn from it. Repeat.