Domain with Google

Ok heres the thing. I have a domain registered with Google and hosted on dreamhost. I want to get rolling with the googles Adsense for domains product. As the domain is registerd with google I understand I have to add a CNAME alias in google what adsense provided me however when I do that enom (as google send you to enom for domain edits) says one has to edit the DNS to default setting in order to add CNAME Now the question is do I have to keep it to default settings or change the DNS to dreamhost.