Change content on courses, professors etc.

Hi there, I've just purchased the Clean Education Pro theme, I want to add the courses and professors to my site but want to change the images and text from the original. How do I change the demo images and content that is displayed to what I want? I've looked at the documentation (shown below) but when I go to courses the content type is not displayed the only thing that is displayed is the option of having it disabled, on the entire site or just the front page. How to select Courses Content Types?# Go to “Appearance => Customize => Theme Options => Courses” Under “Select Content Type” select Post, Page, Category or Content as per your need Finally, click on “Save & Publish” Thanks.