First off, let's familiarize ourselves with the way diagrams are used in this website. The diagrams here basically represent the fretboard of your guitar. Each mark on the diagram represents a corresponding placement of your fingers, either one at a time or simultaneously, on the guitar fretboard and strings.
For example (click image for larger size):
You can follow the chronological sequence of the lessons as presented in this website, or you can decide to try the lessons randomly or according to your preference.
Feel free to contact the author. Details can be found here.
You may now proceed to Lesson 1 or return to the home page and browse the lessons.