Grip the bar with your hands shoulder width apart and your palms facing away from you. Hang with your arms fully extended, you can bend your legs at the knee if they’re dragging on the ground. Keep your shoulders back and your core engaged throughout. Then pull up. Focus on enlisting every upper body muscle to aid your upward endeavours. Move slowly upward until your chin is above the bar, then equally slowly downward until your arms are extended again.
While pulling up, work only with your hands. Any other movements will ruin the technique.
You can bend your legs – it does not affect the training.