Go on the National Autistic Society website.Here you will find a checklist and lots of explanations. Having been in your position 9 years ago my advice to you is to take it all slowly and don't tick everything too quickly as there's no-one in the world that doesn't satisfy some of the criteria as listed!!If you suspect that there is a problem ask your doctor for a referral. Your health visitor should also be made aware of your concerns.

Good luck.