From this post in the knowledge base:
It says:"If you'd like to view your uploaded site on our servers (to check that everything is working, or whatever!) before your domain is up, you can! Simply go to the "Domain > Add Domain area" of our web panel and add a free dreamhosters.com sub-domain (e.g. "yourdomain.dreamhosters.com"). Choose it to be a "mirror" domain and set it up to mirror your real domain that hasn't gone live yet. When you're done, within an hour you'll be able to see your site at http://yourdomain.dreamhosters.com/ exactly as it will be when your domain is transferred!"
I register a domain name: mashow.org. It's not OK now. I want to view my web. But I can't find "Domain > Add Domain area" in the control panel. Please help me to add a free dreamhosters.com sub-domain...
Thank you for your helps....