Watch the Carolina Lady, Pt. 2 online guitar lesson by David Blacker from Lone Wolf Blues
You can use Carolina Lady Part 2 as a sort of solo section to Carolina Lady Part 1. This piece is definitely more challenging as it requires you to keep the steady bass moving while playing some pretty intricate single note lines and double stops, so take it slow and easy.
Within the melody take note of the resolution from the root to the 7th in measure 4. This move sets up the change to the IV chord really nicely. In terms of voice leading the reason the dominant 7th works before the change to the IV chord is because the dominant 7th degree of the I chord in the key of D is a C note which is a half step above the major 3rd of the IV chord which is a B note.
This creates tension over the I chord and is leading the ear right into the change to the IV chord. If that is a little hard to wrap your head around, don't sweat it, the main thing to know is that in a blues it works to setup the change to the IV with dominant 7th tone in the previous measure.
Recommended listening: Chump Man Blues by Blind Blake on The Best of Blind Blake.