Adjust the difficulty with hand position and strength of the resistance band. The further the assisting hand is from the bar, the harder the movement will be.
Ideally you can reach the bar and set up your position with your feet on the floor.
Initiate the pull by depressing your scapula, and then start to bend the elbow. Keep your legs together, and slightly in front to brace your core. Pull until your chin clears the bar.
Descend with control, ensuring you utilise a full range of motion. Repeat for repetitions and switch sides.