When you sign up, you'll find that in your "Welcome Mail" there is a temporary link that can be used to prepare your website:
- In the case of a new site, before the domain name propagates.
- In the case of a site being moved from from somewhere else, you can upload all your content here and then change your nameservers so your site is ready when the domain name propagates.
Occasionally once you've uploaded your content the temporary link doesn't work. If this is the case, it's probably due to a redirect in your code. Look at the address bar and if it doesn't contain the link you put in from your welcome email then you have been redirected.
Unforunately if you are redirecting it for a sepcific reason, the only thing you can do is turn off the redirection (which in some cases can break your site), or wait for the move to go live.