Hello, and welcome to Humankind's Skills Academy.
Click the ∨ button next to the training subjects to show all available training courses in that subject, and click on your chosen course.
You do not have to complete the whole of your chosen course in one sitting - when you want to exit the course, just press the Log Out link and it will save your progress. You can come back to your course as many times as you need to.
You can see how much of a course you have completed by looking at the Current User Progress section, which will be displayed when you are in a course.