Domain Mapping with vps but with shared hosting

ok, this has been doing my nut in.

http://www.example.com = install plus prime

http://www.testing.example.com = sub of example.com

http://www.example2.com = parked domain wishing to push to testing

so I did the IP address and it just went to my control panel. I am using EHCP so my IP addresss isn't example.com

can someone talk in very simple terms, how I resolve this issue :slight_frown: