Only one way to describe this kick… OUTCH!
Though not used in sparring, the Groin Kick is a first learn for most students of martial arts. It’s probably the easiest technique to become good at and it’s also pretty awesome kicking those paddles and shields in that natural upward motion. Keep this ”jewel” in your toolbox for self-defense but don’t neglect to practice it just like any other kick.
Here are the basic steps of the Rear Leg Groin Kick laid out in a horizontal fashion as a quick reference guide. You may get the poster size of this by clicking on the picture.
Now that you have the basic steps, you must practice them and refine your technique. Get those motor skills programmed in and fine tune the mechanics. As I said before, I would work with an instructor on the details because there are a lot of details in between each step and far beyond the scope of this guide.