In addition to this site, I like fastpitchpower.com - very practical advice, great training advice as well.
Carly from fastpitchpower also posts to DFP and is very helpful.
This link does not address follow through, but has good still images of the position of the arm/hand/ball through the back side of the circle, if you explore the site, you can see they teach green follow through style
A Breakdown of Arm and Hand Position in the Windmill Pitch - Fastpitch Power
IR brings the fingers to inside of the ball. The traditional curveball has the fingersand rotating in a couter-clockwise rotation around the side and front of the ball. IR brings the hand / fingers rotating clockwise behind the ball producing a clockwise spin.