First, go to 'Courses' > 'Categories'.
All the Categories that you have already created are listed here. You can also add as many categories as you like by clicking 'Add Categories'.
Click the 'URL' to view the category and the courses within them.
It's a really good way to filter your courses, especially if you have a lot of content on your site.
You can also add categories to the 'Menu' by creating a new menu item, in this case "Marketing" Category and linking it to its URL.
Also watch the video on 'Overview of Categories'