chord formation
 

ok.
start with a c major scale.
C D E F G A B C

triads.
as you saw before, these can be numbered. 1 - 8
C1 D2 E3 F4 G5 A6 B7 C8
to get a triad, all you do is take 1,3 and 5.
so Cmajor triad
C (1 root note), E (3 major 3rd) and G (perfect 5th).
C E G. simple.
thats called a tonic. major.
the different types are:

tonic triad (primary) I
supertonic triad (secondary) II
mediant triad (secondary) III
subdominant triad (primary) IV
dominant triad (primary) V
submediant triad (secondary) VI
leading note triad (secondary) VII

to get these is simple, you just shift the patern up the scale, starting with the numeral on the left...

so a dominant v(5) is G, B, and D
(we've just added 4 to the original numbers, remembering that C is 1, not 0)

Inversions.
you can change a Cmajor tonic, so that C is not the lowest note in the triad.
C E G - E G C
(just remove the low C and bung it in at the top)
this is called the 2nd inversion.
likewise, G C E is the 3rd inversion.
you can do this to any of the triads above.

more than major.
notice we started with a Cmajor scale.
all this applies to other scales.
we can substitute the major 3rd (in this case E) for a minor 3rd. (Eb)
(just count the numbers on a minor scale)

Major triad - major 3rd with a perfect 5th
Minor triad - minor 3rd with a perfect 5th

for an diminished, we keep the minor 3rd and change the perfect 5th(G) to a diminished(Gb)
for an augmented, we need a major 3rd(E) and an augmented 5th(G#)

Augmented - triad major 3rd with an augmented 5th
Diminished - triad minor 3rd and a diminished 5th

four notes.
once you have this down, you can start adding more notes.
example, for a Cmajor tonic,
C, E, G
to make an Cmaj7, you just add the seventh note. B.
C, E, G, B
note: not to be confused with a C7(dominant, or flatened seventh, Bb)
you can add any notes you like.
cmaj2 4 7
C, E , G with D, F, B. (this actually sounds like a bloody mess but never mind.)
if you see a higher number, you need to put it in an octave higher.
1 2 3 4 5 6 7 8 9 10 11 12 13 ...
C D E F G A B C D E F G A ...
so a Cmaj9 would be
C,E,G and D
with the D 14 semitones above the root.
as aposed to Cmaj2
which would be C, D, E, G, with the D 2 semitones above the root.

ill do more later if anyone cares.

Yes, please do - I'm sure plenty of folks (myself included) will find it helpful.

Yeah, haha this might help people understand what I did, I myself probably wouldn't understand it if I was a beginner:p. I can do a "7th chord thread" later, but it'd be later not now. If anyone happens to beat me to it, atleast leave the neapolian and aug. 6th chords to me;).

Sure you mean maj? IIRC, that should be add, as in Cadd9, and Cadd2 4 7, and so on.

i have a question abouth these, well i dont know the nname or even if they are real but they are like harmony chords. I was doing then in A minor (ABCDEFG). what i did is i would just play three notes that were third harmonys of the last note. for example for an A i would play A C E. I was wondering if that is a real chord and if it is what is it called or if you can do that with other scales. prety much i just dont know too much about theory but like the idea of making chords. thanks

Reread the first post. See the part where he talks about numbering the notes? Check it out, lets give your ABCDEFG numbers. A=1 B=2 C=3 D=4 E=5 F=6 G=7. What you did by playing every other note, A C E, is you played 1 3 5. This is a standard chord, otherwise know as a triad.

All basic chords are 1 3 5. Those are the chords that are just a letter like G or just a letter with "minor" attached like Gm.

haha im pretty retarded. thanks though

Ya, thats correct G_urr_A. Chord names can be a real pain in the ass to keep straight :)

C9 = A C7 with the next third added. 1 3 5 b7 9
Cmaj9 = A Cmaj7 with the next third added. 1 3 5 7 9
Cadd9 = A C with the 9th added. 1 3 5 9


And I don't believe there is a chord called Cmaj2, I believe it would be just C2. And i'm pretty sure when dealing with guitar you don't worry about C2's either. I think worrying about C2's is kept with piano's and such, I think those are generally treated as Cadd9's for guitar players. I mean, you could have and play C2's with a guitar, but I think they are just fingered in the same way as a Cadd9. Not 100% sure on that though, if a C2 has different fingering then a Cadd9, I'd love to hear about it! :)

A triad is a 1-3-5 and is relative to the key signature in question.
The A-C-E is a triad, however, it's an "A minor" triad (the 3rd is flattened) in the key of "A Major".

"A Major" triad is "A-C#-E (wwhwwwh) So...A-B-C#-D-E-F#-G#-A
-----------------1--3--5