There are many ways to earn income with online courses.
You can set them up on your own website, like a paid email course, or on a special website that promotes courses like Udemy. You can earn money from a course directly, or you can earn money on the back end (or both).
You can earn money directly with a paid course. There are course websites like Udemy, Fedora and many others. Search for “sell your course online” and you will find plenty of them to help you. You can also set up your course on your own website using a membership website feature like AWeber, InstaMember or even just a PayPal button with a password only website.
You can still make money with a free course. By giving your audience a short free course via email or on a membership on your website, you can use the course to build your email list. You can then promote other things to them through the course and email list. For example, in every email you send about the course, you can include a link to your paid courses.
Remember that for any page on your site (such as the page where you send people to collect the next free module in your course), you can include recommended products that match the things your audience will need to be successful at whatever they want. . are promoting through your course.
You can earn money through all three methods if you wish. It does not matter if a paid course is delivered or not; You can still add add-on products to the delivery page, or through an email newsletter that students sign up to receive.
For example, if you are selling a course on how to write and sell a book on Kindle, you can promote business-related services, such as contractors who will do the work for them. You can also promote software that helps them or peripheral products that they might be interested in.
A series of courses are a great way to earn more money through online courses. This works great if the first course is free, then in order to learn more they have to pay for the upgraded future course.
You can always earn money on purchases. You just have to think about what your audience needs outside of the course, and you can promote those things to them as well. You can make money from the course directly and then make money indirectly by promoting complementary products and services and more courses.