e_h_rochedale south_au's answer appears to be correct. You will need to create a 'index.html' or 'index.htm' file which will serve as your homepage or your intro page.
When you visit a domain, your web browser automatically searches for a 'index.html' or 'index.htm' page to load. If it cannot find either of these files, it will return an error.
So, visiting http://www.mydomain.com essentially means that you'll be visiting http://www.mydomain.com/index.html or http://www.mydomain.com/index.htm.
By the way, the 'index.html' file takes priority over 'index.htm' files if both files are in the same directory.