Hi, I am confused to part of general theory about chords and scales. I am working my way through an acoustic guitar dvd, and he talkes about building chords from each note in a major scale. He plays a g major scale, and then builds a chord from each note.

The bit he doesn't explain is how to know what is major and what is minor. For example. In the g major scale, he makes the chords-

G Am Bm C D Em f#m7b5

I know where the chord comes from (i.e. a A chord) but I don't know why it is minor.

I know how chords are constructed from notes on a scale.

So could someone explain why it is minor and also if there is anything else that i should know about this area. I want to get fully proficient at music theory and why stuff happens, so i would really appreciate any help.
Ok, Lets use C major as our example.

C D E F G A B

You simply use the notes in this scale to construct the chords.

So the root chord is C major, C E G

The next chord is D minor, D F A

Now, this chord is minor because if you look at the D major scale you see that the formula for a D major chord is D F# and A, but the C major scale doesn't contain an F#, it holds and F. This F is the flat third of the D major scale, which as you may or may not know is how you construct a minor chord, So in C, II IV VI and in D I bIII V.

Hope I helped
ok, thanks, so the next chord would be E, G B

which would make a em chord. Am I right?

Could you explain the little bit at the end, don't quite get that

"So in C, II IV VI and in D I bIII V."

Thanks very much for your help, it was very simple after all. I often find in music that it is the simple things that appear the most difficult to understand.
Anytime man, any other questions while I'm lurking around?
it should be F# Diminshed becaus the chords in G Major scale are:

G Am Bm C D Em F#Dim