How to start a blogger blog under a subdomain?

Okay so I recently bought a domain name for my blog, which is a href="http://mydomain.com." rel="nofollow"http://mydomain.com./a Now I want to start a whole seperate blog, because I want one blog just to be about thing, and I want another blog to be about something different but use a subdomain from my original domain so I don't have to buy a whole new domain. So in examples, My domain is a href="http://mydomain.com," rel="nofollow"http://mydomain.com,/a and I want to start another blog under a subdomain, a href="http://reviews.mydomain.com." rel="nofollow"http://reviews.mydomain.com./a How would I go about doing that correctly? I bought my domain through google apps, (which is partners with GoDaddy). I can enter my DNS settings and access all my DNS info, and I want to start a subdomain so I click add CNAME (Alias), the host being reviews since that's the host I want it to direct to (reviews.mydomain.com) and points to reviews.domain.com, since that's the URL I want my subdomain at. Did I do that correctly? Can someone please help? I've tried this for hours and nothing has worked, I just get the server can not be found error in FireFox. Any help is appreciated.