Hi,
where am i able to edit CNAME records for my domain?
I tried in Services » DNS Domain but i didnt find any setting with this name. Should I try with Name Alias or Address?
Whats the difference ?
(I’m using Google Apps and would like to set my mailing to mail.mydomain.com address.)
You already looked in the right place. 
Name Alias will create CNAME records, Address will create A records.
Be aware though that to define where email for a domain is to be directed, you need an MX record, which points to a hostname (not an IP). The record type of that hostname is not allowed to be a CNAME though, it must be an A.
Thank you the answer.