Originally Posted by: axemaster911I am not even sure what you mean by dominant.

Start with a C major scale:

E|-------------------------------|
B|-------------------------------|
G|------------------4-5---------|
D|----------3--5--7-------------|
A|-3--5--7----------------------|
E|-------------------------------|
C--D--E--F--G--A--B--C

Label them all with normal numbers:
C = 1 (1st scale degree)
D = 2 (2nd scale degree)
E = 3 (3rd scale degree)
F = 4 (4th scale degree)
G = 5 (5th scale degree)
A = 6 (6th scale degree)
B = 7 (7th scale degree)

Build a chord (a triad sequence) on every note of the scale using only notes of the scale in the same pattern. I informally call this the "Leapfrog Principle" because you start on a note (C) and "leap over" the next note (D) to use the following note in building the chord (E). Leap again over the (F) and use the (G). Hence, the first chord is C-E-G.

C-E-G = 1-3-5 (the "1 chord") C major chord
D-F-A = 2-4-6 (the "2 chord") D minor chord
E-G-B = 3-5-7 (the "3 chord") E minor chord
F-A-C = 4-6-1 (the "4 chord") F major chord
G-B-D = 5-7-2 (the "5 chord") G major chord
A-C-E = 6-1-3 (the "6 chord") A minor chord
B-D-F = 7-2-4 (the "7 chord") B diminished chord

Notice that every chord has 3 notes - its own 1st, 3rd & 5th unto itself.

E|---------------------1--3-----|
B|-----------1--3--5--3--5-----|
G|-0--2--4--2--4--5--4--5------|
D|-2--3--5--3--5--7------------|
A|-3--5--7---------------------|
E|-----------------------------|
C--D--E--F--G--A--B--C

In music theory we use Roman Numerals to number the chords - usually, upper case for Major chords, lower case for Minor (and diminished). We also refer to the chords by these names which relate to their function in a chord progression:

I - "1 chord" is Tonic (or Root)
ii -"2 chord" is Sub-Dominant
iii - "3 chord" is Intermediate (or Mediant)
IV - "4 chord" is Sub-Dominant
V - "5 chord" is Dominant
vi - "6 chord" is Intermediate (or Sub-Mediant)
vii - "7 chord" is Dominant

(Therefore, a "dominant chord" is a chord built on the 5th note of a scale.)

This is an important point: every note in this listing has 2 separate and simultaneous functions.

1. Its position in the scale.
2. Its position in any given chord.

For example, the note C is the 1st note of the C major scale - the 1st scale degree. But it is also the 5th of the IV "4 chord" and the 3rd of the vi "6 chord".

I did an in depth post about the function of these chords in progressions here: http://www.guitartricks.com/forum/showpost.php?p=194962&postcount=4