Auto body repair & detailing: Dent on roof, heat gun, dent repair

Question
I have a dent on the roof of car. The dent is behind my sunroof. I don't know how the dent got there but my guess is a kid climbed a tree and used my car as a way to get up and off the tree. I have seen video's that uses a hairdryer and a air can. Is this possible? I have also seen the following(www.dentwiz.com). Any help would be greatly appreciated!

Thanks

Answer
Without seeing the damage, I really don't know whether a heat gun or other method would work. Chances are, they won't. If you do not have any buckles or creases, you might try a heat gun, I don't think a hair dryer is hot enough.
I never heard of dentwiz.com, I'll check it out.
I have seen paintless dent repair and usually works well on some small stuff.