Throughout these lessons there will be chord diagrams. Like the one following:
This chord diagram represents a C chord. The vertical lines represent the strings. The line on the left is the thickest low E string. The line on the right is the thinnest high E string. The dark black line at the top represents the nut of the guitar. In some cases, you may also see a fret number indicator on the right of the chord diagram.
The dots represent where your fingers would go to make the chord. When you see a grey, red or different color dot, this indicates where the root note of the chord is. So, in this case there are two root notes in the C chord, 3rd fret of the 2nd string and 1st fret of the 5th string.
Sometimes you may see numbers on the dots. These numbers would indicate what finger you use to play the chord. For instance, 1 is the index finger, 2 is the middle finger, 3 is the ring finger, and 4 is your pinky.
The O’s at the top of the diagram indicate what strings you play as an open string. The X’s indicate the strings you do not play. Either muting it with your fretting hand or not picking it.