Attempting to view your website using the temporary URL 'hostname/~user will not work well if at all with php scripts.
In order to see a site on our server while the rest of the world is seeing it on another server the hosts file on your computer needs edited.
The hosts file, a plain text file located on your computer, is an override of sorts to checking dns externally. It is also called hosts or host with no extension in virtually all operating systems, although the location of the file will vary by OS and even version of OS. More on hosts files here.
In Windows XP it is located inside c:/system32/drivers/etc/ but a search for the filename will give its location.
For your particular operating system simply google "edit hosts file [your operating system]"
Open in a text editor and add your server's IP, which is in the welcome email, and your domain name. For example:
8.9.24.24 example.com
8.9.24.24 www.example.com
8.9.24.24 subdomain.example.com
Your site will now resolve to the server for you, and only you, and be much easier to test before going live.