You must go to a psychiatrist or psychopharmacologist. Your health insurance, referral from someone you know or local hospital should be able to guide you to one in your area.
The best thing to do is to go for an in depth mental evaluation. You don't want the stuff if you really do not suffer from ADD or ADHD, or other conditions a qualified Dr. sees fit for. Be careful there are a lot of quacks who are rx happy. A regular family Dr. can prescribe, but usually only after a diagnosis has been made by a psychiatrist.