Figuring Out The Chords In A Song Lesson by flyinglibra51

There are only 7 notes in a major scale and only 9 (sometimes) in a Minor.
So at first you will use trial an error to identify the correct chord
of the start of a song which will generally be the song's key
signature.

Once you have the Key, and I should stress this is without a capo on your guitar neck, You can sit down with a piece of paper and write out the scale for that key signature. ie C major scale, C D E F G A B.

(capos are fine if you want to change the key of a song so you can
play easier chords if you are a beginner or physically have trouble
making some chord shapes) But you have to figure the song out first!!

Say your song is in the key of C, chords used will be from any order
of that scale.  There may be some accidentals ( Flats Sharps ) 
but you will most likely find all of your songs chords in this scale!!
This is the formula most song writers use. Of course you can also use the relative minor of the scale to figure out some of the chords. In the scales, the fifth note will be forming your circle of 5th's
and the 4th note the flats in your circle of 4th's. the 6th note will be
your relative minor. write your scale twice, 
C D E F G A B C D E F G A B C
          |______________| This is your minor scale from the 6th degree.
                           which is Am of the C major scale.
(Since it is from the C major scale there are no #'s or b's)

The chord progressions used in a song follow a set of rules as well.
Because the root of a chord carries it's name from the scale used,
it also carries its scale degree of that note.

C D E F G A B C   A chords name tells you what the chord is, based on
1 2 3 4 5 6 7 8   the root note. The chord's number tells you what
                  the chord does based on the key signature.

1. is Tonic 2. Supertonic 3. Mediant 4. Sobdominant 5. Dominant 
6. Submediant 7. Leading Tone 8./1. Tonic

When you build Triad chords from ie the C major scale, each triad is
assigned the scale degree of the root in it's name.

Further, the scale degrees are assigned roman numerals for the different
scale degrees. Capitalized numerals for chords with a major 3rd and 
lower case numerals for minor chords. Diminished would have the small
degree symbol o beside it's numeral and augmented with a + sign.

Triads contained in the C major scale (capitol M is major)

CM  Dm  Em   FM  GM  Am  Bdim                     CM
 I  ii  iii  IV  V   vi   vii(with degree symbol)  I

So the chord progression follows the ascending scale but in a song
it doesn't mean all of them are used. But the ones used will be in 
order shown above, more likely than not!!

Now you have all the information you need to finish your song. At first 
trial and error will work for you but eventually you will train your ear
and soon you will figure out a song in no time.

Of course there are those pessty 7th chords but you will have them 
figured out in no time. Some of the diminished and Suspended chords
will give you pause but once you educate yourself on how chords are built, you will soon master them as well.

This is my first post so bear with me. If you have a question about 
this, just message me and I will try to help you. Thanks for reading!!

flyinglibra51
God Bless Glen Travis Campbell