I've installed from Godaddy also and what I do is move the contents of the joomla directory to the document root directory using an ftp client (such as FileZilla), then change the configuration.php as follows: all lines that mention the path (such as /home/content/m/y/d/mydomain/html/joomla or /home/content/m/y/d/mydomain/html/joomla/cache) should have the joomla subdirectory taken out (so it's /home/content/m/y/d/mydomain/html or /home/content/m/y/d/mydomain/html/cache).
An alternative to moving the files would be the php redirection code. In your document root your index.php file would have this code and nothing else:
<?php header ("location: http://www.mydomain.com/joomla"); ?>