An aeromechanic is a mechanic who works in the aircraft industry.
You can check your yellow pages to find your nearest local aeromechanic garage. Once you find which one is the closest and then take your car there to get it fixed.
To become an Airframe and Powerplant Mechanic (A&P) you have to get a license from the FAA which requires either a school which specializes in aircraft maintenance or military experience and training equal to that schooling or both. You can go to the FAA's website at http://www.faa.gov/licenses_certificates/airmen_certification/ and get answers to all of your questions.