Originally Posted by tchambliss

The 7(with line through it) symbolizes that it is a major 7th, if you dont have the line through it the 7th chord is a dominant chord constructed from the Mixolydian mode. The - symbolizes minor of course and I can't make some of the symbols like a 6 above a 9 in a time signature except not for the same purpose so please just bear with me. The things in parentheses are really just an awkward way of writing something that I am not sure of how to write on the computer.

Triads......................Steps of major scale............Chord symbol

Major chord..............I- III- V............................A
minor chord..............I- bIII- V...........................A-
Augmented chord......I- III- #V ..........................A+
Diminished chord........I- bIII- bV...........................A(temperature symbol)
Suspended chord........I- IV- V...............................Asus

Major chord with tension

Major 6th chord...........I- III- V- VI.......................A6
Major 7th chord...........I- III- V- VII........................A7(with line through 7)
Major add 9 chord.........I- III- V- IX.......................Aadd9
Major (six above nine) chord I- III- V- VI- IX............A (six above nine)
Major 7th add 6 chord....I- III- V- VI- VII..........A7(with line through it)add6
Major 7th add 9 chord.....I- III- V- VII- IX.........A7(with line through it)add9

Minor chord with tension

Minor 6th chord...........I-bIII- V- VI.....................A-6
Minor Major 7th chord....I-bIII- V- VII..................A-7(with line through it)
Minor Add 9 chord.........I-bIII- V- IX....................A-add9
Minor (6 above 9) chord...I-bIII- V- VI- IX...............A-(6 above 9)
Minor Major 7th add 6 chord..I-bIII- V- VI- VII..........A-

I'll edit this and continue it later, have to go for now, I'll finish it tomorrow sometime. This will get you started though.