There are many, many, online course platforms available these days. Some are "hosted", which means that you register, pay monthly and organize your course with them; It's easy, but not very flexible.
Another option is to go with a self-hosted option, most come as a WordPress add-on. Therefore, you will have a WordPress website as a base, with a complement of the system of courses to teach the courses.
It depends a bit on what kind of courses you want to offer: live prerecorded video? Do you want a lot of interaction between students, etc?
I am using LifterLMS for one of my own websites and I like it a lot, but there are many others. I have tried many different plugins and I liked the best one.
I am also a web developer. I can help you configure everything (hourly rate or fixed price).