You do not have to read music to play basic guitar. This article explains how to interpret chord diagrams on sheet music and play them on the guitar.
One of the things you encounter immediately when reading sheet music is the chord symbol. This is the musical symbol that describes the harmony at a particular point in a piece of music. An example is Gmi7. This tells you that the chord is a G minor seven chord. But, what notes do you use to play a Gmi7 on the guitar?
Sheet music for popular songs very often has guitar chord diagrams above each staff showing you how to play the chords. These diagrams make it possible for you to play a chord without knowing what the chord symbol means, or what notes are in the chord. The diagrams simply show where to put your fingers on the strings on the fretboard.
Of course, you as continue to study guitar and music, you will probably want to learn music theory to understand chord structure and the notes used for all the important chords in all twelve keys. But to get started making music, this is not necessary thanks to chord diagrams. They are far simpler than interpreting complex chord symbols.
A guitar chord diagram consists of a grid of five horizontal lines and six vertical lines representing the guitar fretboard. The diagram is a miniature picture of the fretboard as if you were holding the guitar up in front of you and looking at the upper part of the neck.
The vertical lines represent the guitar strings. From left to right (low to high pitch), the lines represent the strings E, A, D, G, B, and E.
The frets are represented by the horizontal lines. The thick line at the top represents the nut of the guitar at the end of the fretboard. Hold your guitar out in front of you and look at it, and all this will make sense.
The dots on the vertical string lines show where to put your fingers, the notes you fret with your left hand when playing a chord.
The numbers below the string lines at the bottom of the diagram indicate the finger of you left hand to use to fret the note. 1=index finger; 2=middle finger; 3=ring finger; and 4=little finger. Normally, the thumb is not used to fret.
The X or O above a string line means that string is open, or unfretted. An X means you do not play the string with the right hand, and an O means you play the open string.
In cases where a chord begins on a fret other than the first fret, a number on the right side of the diagram tells what the starting fret is, such as 2fr, 5fr, etc. Chords that use the first four frets often use open strings and are simpler to play. Thus, they are more common in chord diagrams.
That is about all there is to it to get started. When you look for sheet music or music books, just make sure they have guitar chord diagrams, and you can start playing basic guitar right away.