How to use “DNS” and “CNAME”?

I tried to use a “CNAME” Record today to link my sub domain as below:

CNAME Record

Host: xxx.myhostname.com Value: xxx.otherhostname.com TTL: 7207

It’s actually working, but the problem is that main domain “myhostname.com” still not linked.

The question is if is it ok that i use the Name server of my hosting for the complete domain and CNAME for the sub domain together?.

and if not possible how i can link the main domain to my hosting space?.

Regards.