Dumbells in hand and down at your side. take a lunge step forward kepping your trunk upright with feet, knees and hips aligned pointing forward and not out to the side.
You should feel the glutes and hamstrings of the lunge leg, quads and hip flexors of the trailing leg, and the upperback and misection keeping you upright.
As you push off to standing curl the dumbells to your chest, while keeping elbows tucked in and pointing forward. Repeat with the other side.