The frame at right-bottom shows the the PDF file diplaying TeX typesetting. Full view of each frame can be had by sliding its boundary. If the frame you are now reading is too narrow, open it up a little more so that you can read comfortably. View the slides and the PDF file Full Screen or according to your taste. You can step through the slides using the buttons on the side of the screen.
Slides contain descriptive material and PDF file gives the mathematical details.
You can shuttle back and forth between the two, by sliding the boundary between the two.