This may be due to your default file not being set.
Go into your panel and then go to Domains --> Click your domain and choose Properties
then choose Domain Properties--> URL Redirection
In here you will see the default files. Add your default file name. (Ex: index.php)
Choose Save and refresh your website page.
If you still cannot see the page make sure you have uploaded the file you are trying view. If it is not there, then upload it using an ftp client to the folder you are trying to access off the website.