Login to Learnyst as Admin and go to Courses and click on Create. Here while you create the course you can set the pricing for your course. If you are creating a free course just click on Free check box else enter the price for your course and click on Create button.
You can also set the pricing or change the free course to paid one after creating the course. To do the same go to Courses-->Your course-->Settings-->Basic Settings--> Course Pricing. Uncheck the Free Course check box and then enter the price for your course.
Once you have entered the price click on Save to save the changes.