Hey Friend,
The next chord coming up in the key of D major is our good friend A major. While I haven't covered it in any depth in this series yet, we have looked at it as part of the CAGED system. It's the "A shape" (duh), which can be moved up and down the neck for quick chord play.
As the V chord in the D major harmonic progression, A major holds an important spot in the key. It's at the midpoint of the key sonically (when you look at its frequency), so it plays a big part in songs as a landing place for providing resolution. Any V chord in a key give a verse or chorus a solid place to land so the phrase doesn't sound shaky or unfinished.
A major is made up of the A, C# and E notes. It gets its notes from the key of A major, using the 1 3 5 notes from the scale.
1 2 3 4 5 6 7 A B C# D E F# G#
Since we're learning the key of D major, the three notes also fit inside the D major scale.
D E F# G A B C#
To play an open A major chord, you're going to use the open fifth string. Place your middle finger on the fourth string, second fret. You index finger comes next on the third string, second fret. Finally, your ring finger goes on the second fret of the second string.You can also strum through and play the first string, since it's open E.
Now you might think that little area is too cramped for three fingers to scrunch in, but if you move your index finger up a little inside that second fret so it sits on top of the other two fingers, you can make it work. Or, you can simply barre all three strings with your index finger.
Barring the strings makes it easier to slide up the neck if you want to use that shape for another chord, so it makes sense to practice both fingerings. I personally use the first fingering when there's any picking involved versus straight strumming. And if you happen to be rocking a distorted tone, you may as well just use the barred version, because it's going to come across as a power chord anyway.
I don't have the exercise files quite ready, so I'll get those finished up and sent out tomorrow. Have a great one!
Peace~
Dave | 
