If you want to try to figure it out, grab a buddy and a camcorder (or forego the buddy) and shoot a quick video (from the side, please. Or optimally, from a few angles) of the following:
A few air squats. (Just a plain squat. No bar, no weights, just bodyweight.) Don't halfass these, a good air squat is critical do a good weight-lifting squat.
A few squats with a broomstick (or something similar). Pretend there's a good 100lbs on it, but just use the stick.
A few squats with just the bar. Same as above, pretend there's a bunch of weight, but don't actually put any weight on it.
It's stupid to work backwards when it comes to form. You should start by having a perfect air squat, and then the next step is a perfect squat with a broomstick, and then the next step is a perfect squat with just the bar, and then start adding weight slowly until your form suffers. If we were in person, I'd watch and help and correct you during each of the above steps, but... internet. But we can still pretend!
Also, if you want to kill two birds in one stone, do deadlifts too. I'd skip the "air deads" and jump straight to the broomstick, though... :p
A few things to note with the video: Please make sure your entire body is in frame. I want to see the top of your head, and the bottom of you feet. Like i said before, I want predominantly side-shots, but a few front and back could help identify, or at least give me a good way to show you, other problems that I can see.
When you've taken them, toss 'em all in a zip and you can email them to me, or upload to youtube, or something.
If you want to learn more about the basic olympic lifts (deadlift, squat, overhead press, etc), I HIGHLY recommend a book called "Starting Strength" by Mark Rippetoe. The first chapter is called "The Squat." It is sixty five pages. About the squat. More than you ever thought possible to know about the squat. Written at a level everyone can understand, from your layman to your doctor, it is VERY educational.