If you think your child has Autism you should take him to his pediatrician and say that you would like him tested. Even if his Doctor doesn't think he has Autism ask them to do the testing anyway. If you catch it early it's much easier to deal with in your child.
YOu will need to take your child to a doctor that is liscensed to test for autism. Take him/her to their regular doctor and they can give you a refferal.
Insist the school system test your child if you suspect autism. By lae they must do this. Be persistent and even send the request by certified mail to proved you requested it.