Make an appointment with a counselor at your local community college. They will often be able to help you find accredited vocational schools within your area of interest, or point you toward a program at the community college.
Do a simple search online. The RWM Vocational School Database, Trade-School.org and the Trade School Guide offer excellent searchable databases to find exactly what you need.
Look for a program that fits what you're wanting to do, but also fits your budget and time frame. Many vocational schools offer expensive programs, and as such, you can often get the equivalent education or degree at a local community college.
Look for government programs like Job Corps. Job Corps is a residential program that helps students age 16-24 earn high school diplomas and receive education at vocational schools for free.