First of all, those pictures are called chord diagrams. The diagram grid is the fretboard "goods" and "strings". So, there are only six vertical lines in total***, where the leftmost vertical part is the "sixth string", which is the thickest chord, and some of the second vertical lines from left to right are the numbers of the "first banjo".... ... etc. The black circle in the picture is where you leave your current job, according to the fretboard. The black circle in the picture corresponds to your left side is the "name", where the index is 1, the middle finger 2, the finger, and the pinky 4. The white circle in the picture, which is meant to explain what string this is, is not pressed, and is called "empty string." The figure below is to illustrate that you do not press the string fork, but unlike the white circle, the figure of the circle that does not belong to the white belongs to the chord sound, the chord and the black figure of the fork sound. Similarly, the F chord refers to the chord that is held down using a whole row of fingers on the whole root of the thick line, which is also called "horizontal press." What kind of finger is this supposed to be, then you have to look at the thick black figure inside. Oh yeah, and another point of the chord diagram is that in the upper left of the diagram, there is a digitized X, which refers to the product of the digit X on the right as "the first X." The upper left of the X in that diagram. Yes, this shows the chord diagram for the first launch of a product. Well, this is the most basic way by chords.