added new user account not able to access website

Hi I have a clean install I have added domain name and name servers etc it is setup under mydomain.com however I want use mydomain.com for my own website so is it possible to have the control panel install on a sub domain so I can still use my domain as normal or will I need a domain for the control panel and another domain for my website ? 

if I try to access mywebsite.com or www.mywebsite.com

I get http://prntscr.com/72wwar


thanks

Mike