This grip is used frequently with the chefs knife. The thumb and forefinger cradle the blade and the remaining fingers curl around the handle. This hand position allows for the greatest control when chopping and slicing food. For chopping food, the tip of the knife touches the cutting surface and the hand rocks the knife in and out of the food without lifting the knife off the cutting surface, back and forth, in a slight rocking motion.
This grip is used frequently when dicing food with the second hand holding the tip of the knife down. The knife is rocked up and down, back and forth. The strong grip is also used frequently when slicing food. Note all the fingers are wrapped around the handle.
Hopefully these techniques are helpful to you. Remember to be careful when using a knife. It is important to use sharp knives and to take care of them. I hand wash my good knives and hone them slightly after each use. This keeps them from getting thrown around the sink and dishwasher, keeping their edges sharp. Always know where your fingers are and avoid getting them too close to the cutting edge.