In case of this exercise mostly the hamstring and the glutes are burdened, secondarily the spine straining muscles, the abs and the muscles of the forearm and the muscles around the shoulder blades.
Stand in a narrow straddle, feet and head facing forward then grab the bar in shoulder width. Bend slightly forward with straight back. Hold the bar closely in front of your body and then place it below your knees by slightly pushing back your hip (buttock). In the lowest point let your hamstring totally stretch then strain your buttock and then elevate to the starting position with a slow but firm move by pushing your hip forward.
When you place the bar down, inhale, when you pull it up, exhale. Your back SHOULD NOT BE curved during the exercise. Hold your waist in a slightly hollow position or at least straight during the whole exercise. The aim is always avoiding the risk of injuries. The arms function as hooks here as well, you should not help the lift with your back.
You should be careful picking the weights, especially if you are a beginner because the spine and the lower back section are subjected to an increased burden during the exercise.
I suggest that you should become familiar with the motion itself in the first (few) round(s), learn the right execution and get a feel on which way you can involve the hamstrings in the work. Don’t focus on the bending itself but on letting the weight down, don’t lift the weight with your waist but with the help of the strength of your thighs. You can reach this easily by not launching the motion by straightening the torso but by contracting the glutes and pushing the hips forward.
Pay attention that when lifting the weight you don’t have to force your upper body go backwards in the upper position. If your upper body is beyond the upright position then the strain will be provided by the lower back section instead of the thighs and the glutes.