Hey Friend,
We started talking a little about the Circle of Fifths yesterday, and from that, we figured out that if we're going solely off the number of sharps (#) or flats (b) in a key, the next logical choice to study would be the key of G major. G major has one sharp note - the F# note.
Here it is again:
G A B C D E F# (G)
All the notes are identical to the key of C major except F#. How do we know for sure?
Well, I just apply the pattern we learned a while back that gives us the scale. Remember W W H W W W H (or T T S T T T S)?
That's whole, whole, half, whole, whole, whole, half, for the uninitiated (tones or semitones).
Again, what that means is, for every whole step (or tone), you move up two frets for the next note. Every half step (semitone) is only a one fret difference. No matter what note you start with as your root note (AKA the tonic), the pattern will give you a major scale for that key.
The Circle of Fifths tells us how many sharps of flats, but we still have to determine which note is the sharp or flat.
Since we know the key of C is straight up natural notes (no sharps or flats), we now that the spaces (or intervals) between each note will always be that way. The space between a D and D note will always be two frets. Between G and A, two frets. From B to C, though, always one fret. And it's the same between E and F - one fret. Here's C major again:
1 2 3 4 5 6 7 8 C w D w E h F w G w A w B h (C)
And here's G major:
1 2 3 4 5 6 7 8 G w A w B h C w D w E w F# h (G)
The relationship between each note stays the same, but because we apply the pattern to create the scale, The F note had to shift by one fret, making it F#.
Look at the C major scale again. E and F are next to each other on the fingerboard, one fret apart. But because we need to have a whole step between the notes 6 and 7, and E and F happen to be the notes that fall into that position, we need to shift the F note over one fret to get F#.
Make sense?
It takes a little getting used to, but if you can remember that C major is the gold standard to know exactly how the interval pattern lines the notes up, and you can count to five, you should be able to figure out each key.
Don't worry, I'm not going to leave you hanging. I've got a little process you can use to get yourself up to speed determining the notes in a key (and consequently all the notes you'll use for the chords in the key).
We'll look at that tomorrow. Send me your questions, and Rock ON!
Peace~
Dave | 
