The power should come from the hip in pushing the bar up, to help with this stand wide grip of barbell, knee slightly bent, hold the barbell just below the hip crease.
From this position I want you to push the bar up with your hips and your arms guide it up in a straight line then you catch under it by coming under the bar and pushing elbows out and land in a quarter squat.
Done.
Then when you can do that, from the floor move the bar up keeping contact with the bar and your body till it reaches that below the hip crease area and the rest is the same.
Tricky part is to do it in one smooth motion, which you can get through practice.
also since starting, the grip should be with the fingers wrapped around the thumb.
good luck with it.
