2005 STS how to check trans/differntial fluid

Can someone tell me how you check the transmission fluid and rear differential oil on a 2005 STS? The owner's manual says "have your mechanic check it when in for service." Yeah right, I'd like to do that myself, the Chilton books are not available at Autozone, I guess Cadillac really doesn't want us working on our own cars. I sleep better at night knowing I check these things myself.

Thanks!