Hey Friend,

Yesterday, I quickly went over the pitches (or notes) that make up the key of D major. Here's a quick review: D E F# G A B C# (D)

As you can see, each pitch has a different letter assigned, and the pattern repeats itself starting with the eighth note. That eighth note is called the octave, and you can consider the scale a closed loop. Once you hit that seventh note in a scale, it starts all over again. The only difference is, the pitch is higher.
Try it. Play the sixth string (low E) and the second fret, fourth string (D). Those two notes are E. You can hear they're the same notes, just different in pitch.

The chords that form the basic progressions we use can all be created using that scale. That means the scale has the correct notes to make Em, G, Bm and so on, in addition to D major. 

Here's a recap of the base chords in the key of D major: D, Em, F#m, G, A, Bm, C#dim

Each of these chords are known as triads because they have three notes. Those notes are the one, three and five notes from the scale they're named after. Depending on the type of chord (major, minor, diminished), the three or five note can change.

Alright, this stinks. The chain pulling back to work is getting yanked. I'll have to continue this tomorrow. Sorry...

Peace~

Dave