In the full lockout position, keep your heels on a box, adequate to suit your level. This may take some trial and error.
Next, launch up to the bar reaching the standard of chin over bar. When you come back down to the box, you can increase the level by going down with an eccentric, or count of 2 or 3 seconds.
Remember to seek the advice of your fitness trainer, medical and/or allied health professionals, if you are new to exercise or have an injury or medical condition to consider.
See more Gym Exercises HERE
See more Strength Exercises HERE