The D7 Chord is found by first locating the 1, 3 and 5 positions (D, F# and A) of the D Major Scale: D E F# G A B C# D, and then adding a flat 7 note. To locate the flat 7 note, we first find the 7th note of the D Major scale (C#) and then go back a 1/2 step to the C.
So the notes of the D7 Chord are: D F# A C.
Here is a key that will help you read the chart:
This second D7 chord is technically a chord inversion because the D note is no longer the bass note or lowest pitch. The A note now becomes the bass note. It is still referred to as a D7 chord though. If you play it, you will notice it sounds just like the D7 chord above only it has a fuller sound because we are adding an additional A, or 5th position to this chord.
D7 Guitar Chord Video
The video below will further demonstrate how to correctly play the D7 Chord. Enjoy!