a) Having a simple website is easy these days. You do not really need to make it fancy. Keep it simple. Some freelancers will do it for as low as 20$ and having a webpage is useful because it is more professional and adds more legitimacy.
Here is a service you can check out: http://www.3dw.trade

b) You can sell your services through many freelancer websites. Google freelancer websites and you will find fiverr,upwork,guru and others. You can list yourself as a seller and get going.

c) Register here https://www.mylanguageexchange.com/ and see if people want to then go the extra mile and actually buy your course.

Best wishes.