Check out these videos on how to do air squats with good form.
AIR SQUAT KEY POINTS
Thighs to parallel
Keep your heels grounded
Try not to lose balance and move towards your toes
If you cannot go all the way down to parallel then practice sitting on to a box (or the toilet).
Sit down on to the box and then sit back up. If you need to use a side railing for assist then do so.
SGPT Video Squats and Lunges
This is a life skills exercise. The longer that we are able to perform squats with good form is a good indicator of your longevity. Practicing squats daily and using them in your workouts is a great way to stay fit long term.