When you go to www.yourdomain.com, the web server will look for an initial "default" (index) page to show...in the following order. This page must exist in the public_html directory of your web space:

index.html
index.wml
index.cgi
index.shtml
index.php4
index.php3
index.php
index.phtml
index.htm
default.htm
default.html
home.htm

If none of these pages is found on the server, your "site" will be a directory listing of the files and folders in your space.