Your best bet is to go to college.
However, if you are dead set on not doing that, then you should hire a professional (not a friend with a camcorder) to film a kicking session of you kicking field goals, kicking off, etc. and store it in DVD format. Then, send a copy to each of the special team coaches and kicking coaches (if applicable) of each NFL team.
However, I can tell you that at 19, no matter how well you kick, you cannot play for an NFL team.
NFL rules state that you cannot play in the NFL until you have been out of high school for at least 3 years.
Your best bet is to contact the special team and/or kicking coaches to make them aware of you (if you really are good) so that in the future, they will already know about you.
-Reality