In the actual diagrams in the lessons, you will see dots on the fretboard marking where the notes should be played. They will be in various colors and will mean various things so I will leave those explanations until the lessons.
Also, if you see note markers that are all the way at the end of the neck, and are not in between frets where you would put your finger, but rather right on the "nut" at the end, these are "open" notes and do not need to be fretted at all.
* note for bass players : Bass players can use the exact same diagrams as the guitar diagrams, using only the bottom four strings (low E, A, D, G). This means that everything is the same for bass, you would just ignore the B and High E strings. (this can change for 5 string basses, etc)
** note : Diagrams made special for bass will be coming soon.
