1) Step on one side of the band and grab the other with your hands with your palms facing up. Keep your hands at shoulder width apart.
Do not fully extend your elbows and keep them at a slight bend. This will apply extra strain on the biceps.
2) Exhale and curl the band up towards your chest. Make sure that you are moving only your elbow in the process - this will ensure that your biceps is the only muscle being engaged.
As you are raising the band supinate (rotate) your palms (leading with your pinky finger) out.
At the top of the movement squeeze your biceps.
3) Inhale and slowly return the band back to your starting position. Remember to rotate your palms back to their starting position too.