http://www.ehow.com/how_5752265_identify-warning-lights-toyota-camry.html
Your light should come on according to the above link when you set the key to the II position, along with other dashboard lights, and be the one light remaining on after a few seconds. If the rest of the lights come on, but the CEL doesn’t, and if you bought the car used, the plastic display cover might have been painted with black paint to hide the light, a sneaky old trick to sell a car with a problem. Otherwise, honestly, I have no idea. I’d suggest using the scan tool on as regular a basis as you can manage.