There are many "Question and Answer" websites, where user ask question and other users answer them.
Some Q&A websites
Create account is such Q&A website, answer the questions related to your course. Don't forget to Ad image and link (to your course home page with your affiliate ref id) in the answer so readers know about your knowledge and come to visit your course.
We have to answer good question only once and get repetitive traffic to home page of our course.