You can always open a new site with that domain name and once your site is uploaded and working properly contact the registrar of that domain name and have them update to point the name servers to us. You do not need to have the domain name resolving to our web server. With the new account/site you will be issued a secondary URL and FTP address. This will still allow you to connect to our server and upload files and view them from your browser.
Thanks. Do I need pay extra for this process to you or the domain name registra or my current hosting?
No registrar would charge you to update name servers. Your current host doesn't have to do anything (assuming they are not also the domain registrar).
Just to clarify one last point: Can I change the domain registrar of an existing domain to be Winhost with some kind of process?
No, we are not a domain registrar. If you are unhappy with your current domain regsitrar, you can choose another domain registrar and move your domain to them. You would keep your domain at your domain registrar and pay them for all the doamin renewals and do your hosting with us.