This is an introduction to the major scale and how to build chords.
The C major scale
The major scale is all important in music, in particular, the c major scale. Practice the tab to get an idea of what it sounds like and how it is played on the guitar.
The major scale is used to build up chords in that particular key. The major chord in that key is built up of the [ 1st, 3rd and 5th ] notes in the scale This produces a c major chord.
Other chords in the same key (useful to know when composing) are built up of the:
[ 2nd, 4th and 6th ] notes (making a Dm chord)
[ 3rd, 5th and 7th ] (making an Em chord)
[ 4th, 6th and 1st ] (making an Fm chord... notice how we've looped around, because the 8th note is the 1st)
[ 5th, 7th and 2nd ] (making a G chord)
[ 6th, 1st and 3rd ] (making an Am chord. This is special.... the 6th chord in any major key is called the relative minor)
[ 7th, 2nd and 4th ] (making a B diminished.. Also special as moving this chord down three frets produces the same chord, with a different root note, hence the chord can be named after any of it's notes, sounds freeky as well!)
Remember that all of this applies to any major scale / key. All you need to do is adjust your starting point accordingly. And, the chords in the key of a minor key are exactly the same is it's relative minor. So you could write a song in the key of C, but it could be in Am, depending on the root note of any melodies you are playing. There will be more on this soon, when I talk about modes.
The c major scale is important because it contains no flats or sharps. So if you need to, you can use the c major scale as a means to find the name of any note on the guitar by starting on the nearest C and working up or down the c major scale to find the name of the not you are looking for. If it is not in the c major scale, then you can name it either "sharp" (#) if it is one semitone higher than the c major scale note, or "flat" (b) if it is one semitone lower. I will cover this in more depth when I talk about the chromatic scale.
You can learn the major scale in many different shapes to cover the whole fret-board. But I think it is easier and more fun to begin with the minor pentatonic. This is used in many rock and blues riffs and solos.
You can then discover that the major pentatonic as the same as the minor, but just three frets down. AND THEN you will find out that the major pentatonic scale is in fact the major scale with the half steps omitted. So all you have to do is find out where to slot them back in, and voila! you have the entire major scale covering the whole fretboard.
Stages of Mastering the Guitar