http://www.bodybuilding.com/fun/no_pain_squat.htm
Step 1:

Face the wall, direct your nose and eyes looking upward. Your chin, chest, and toes should all be touching the wall in front of you. Your toes must be pointed outward in a 45 degree angle.

Step 2:

Stand with your feet about a foot length wider than shoulders, and then raise your arms above your shoulders, about even with your ears, the palm of your hand should be touching the wall at an equal distance away from your head.

Step 3:

Now look up and this should help you arch your back. Stick out your chest. Lift your toes slightly. This forces you to keep your weight on your heels.
Click To Enlarge. Step 3.Step 4:

Sit back and down a few inches at a time. Be sure to maintain your chest being parallel with the wall. Try to reach back with your buttocks, while keeping your chest parallel to the wall.

Step 5:

As you lower yourself, tighten your abs, and keep your toes elevated just slightly, to push your weight on your heels.
Click To Enlarge. Step 4 - Step 5.

Step 6:

Click To Enlarge. Step 6.

Step 7:

Rise up from the lowered position by driving your hips forward (like someone is pulling on a rope tied around your waist). Exhale and inhale at the top of the movement only.
NOTE:
If you are having trouble getting low enough with the squat, try spreading your legs wider and make sure your toes are at a 45 degree angle to the wall.
Edited by AwesomeAries - Dec 30 2012 at 12:10pm