This clear and simple video demonstrates 6 levels of push-ups starting from complete beginner, the demonstrations offered are:
Level 1: Incline Push-ups on a bar
Level 2: Incline Push-ups on a bench on knees
Level 3: Incline Push-ups on a bench on toes
Level 4: Floor Push-ups on knees
Level 5: Floor Push-ups lowering down on toes, pressing up on knees
Level 6: Full Push-ups (on toes)