Hey Friend,
Like we saw in the key of C major, the C major chord follows the B diminished chord in the harmonic progression of A minor. The difference here is that this time around, C major is the III chord.
It's still major, but now C is occupying a different position in the scale. Rather than a tonic position (the 1 note), it is now a major third.
A Minor Scale:
1 2 3 4 5 6 7 (8) A B C D E F G (A)
C major will still be constructed from the C major scale, but the same notes are present in the key of A minor - C, E and G (occupying the 3 - 5 - 7 positions in the scale). Because a major chord comes from the key it is named after, and it is constructed using the 1 3 5 notes from that key, we look to the key of C major to explain its notes.
1 2 3 4 5 6 7 8 C D E F G A B (C)
Your exercises, Madames et Messieurs:
Here are the various positions up the neck where you can play C Major.
And its barre chords:
Gotta roll. It's a new week and time waits for no one...
Peace~
Dave | 
