In a standing position, place your upper triceps and chest against the padding so the corner of the pad is in your armpits when holding the E-Z curl bar. Use an underhand grip on the insides of the bar. Also, use safety clips to keep the weights stable on both sides.
Start the curl by tensing your biceps and bending your elbows until you bring your hands up and in line with your shoulders. Then slowly lower the weights back down by extending your elbows to a point where they are almost straightened but do not lock them out. Ensure that your wrists stay aligned with your forearms and that your triceps stay in contact with the padding at all times. Repeat for the desired amount of repititions, then gently rack the bar.
Avoid using excessive momentum by leaning back to curl the weight towards yourself, be controlled throughout.