How do I access my admin account if my site points to parked nameservers

I would like to work on my website and be able to view it without making it public so that everyone can see it. So I pointed my domain to parked name servers, but I realized that now I can’t get in to access it. Is the only way to access your account to log in through the home webpage, or is there another url or site you can go to to access the admin account? Can you view your website as it is built and see how it looks without allowing anyone to access it yet? I am using the application off of a hosters server. Does it make a difference if I had the application downloaded onto my computer? In general, is that a better way to run wordpress or does it work just as well off a hosters server? This may be an easy question, and I might just be missing something, but I would appreciate anyone’s help.

Thanks