becoming a ref in PA

[K-low]

Best place to start would be http://www.PIAA.org in PA.
You can register for exam there and you will recieve rule book, sample tests etc.
After passing test in PA. you have 15 days to affiliate with a local chapter in your area. (You will be provided with appropriate contacts)
Local chapters will oversee yor training. They usually provide clinics, peer-mentoring etc.
Most likely they'll start you off with grade school, AAU, and rec leagues, and you should be able to work up from there.
GOOD LUCK