headers

i was wondering how hard it is to install headers...i have very limited experience with cars, and was wondering if anyone could do it or should i take it to a professional.... also how much HP would they create....

That depends on several things. Lt's are generally harder to intall than shortys. Lt's tend to add a little more power than shortys, but thats mostly for built motors.
If you have little to no experience under the hood than you should deffinately go with shortys if you want to put them on yourself. Also there are tons of shortys you can buy that boly up to stock exhaust. But if you would rather not get stuck trying to put headers on, and be without a car for a while if you get confused, or if something doesnt go as smoothly as planned (which it rarely does), most exhaust shops will put headers on for a price.