It’s sort of hard to explain but try using a lower weight and experimenting with tutorials you find online. Lowering the weight will allow you to experiment without much risk. As for what I can try to explain try and like squeeze the flute at the top as your goal, I think it’s more of a hinge motion if that helps 🤷♀️
For me I have to focus on tucking my pelvis so that I’m really doing a kind of scooping motion under the bar. The best way I explain it to people is do the over exaggerated back arch that girls would do in like middle school to make their booties look big, and then move ur hips the exact opposite direction, pull them into your belly button. When ur pelvis is tucked like that it helps prevent strain on lower back
Try lowering the weight & align your hips with your ribs, & then tuck your ribs, you might feel like ur hunching since your on the ground? But when you go up your back should feel straight and when you do the movement you should feel like ur just hinging at hips really. there shouldn’t be a lot of pressure on your heels/toes/feet, and you shouldn’t have to push ur upper back into the ground a whole lot.