Until you've been diagnosed with ADHD, any doctor who is responsible isn't going to just give you adderall because you ask for it. It's a controlled substance, and it's a popular abuse drug right now. If you think you have ADHD, get a decent psychiatrist and work with him or her. Get a diagnosis, and try some medications. Take whatever is prescribed, and if it doesn't work, try something else.
Taking Adderall is a real commitment. If I can't get the drug for some reason, I'll end up sleeping 16 hours a day for maybe 3 days. You're not going to want to enter into that lightly, and there are other medications besides stimulants.