In DirectAdmin, the default message you get when accessing a page is “Apache is functioning normally”. This is good to know, because if you see this message, it means Apache is working and returning a reply.
However, if you want to change this page to something more informative or user-friendly, you should edit the file locatd here:
If you want to edit in via SSH, you can use this command to edit it in PuTTY:
sudo nano /var/www/html/index.html