Use domain mapping in couple multi sites in the same server

Hi,
i want to use domain mapping in couple multi sites in the same server.

my main multisite working well i just point all the domains with A record to main ip or use a parked domain.
now in the same server i create new subdomain that have new multisite.

the question is how can i map domains there?
A record to the main ip? i try but can't get this work.
maybe Cname? but how to name this work?

main site: http://www.mysite.com
new multisite shops.mysite.com

Thanks