And its a very scary thing to know that such an inexperienced person is running a server on the internet. And that is no disrespect to you. We all did not know at one time. But you really should know how to do basic things before trying to run a server on the internet where it is exposed to hackers and worms and all kinds of bad stuff.
Even people who only run web sites and not a server know what to do with "permission denied" messages. A server administrator certainly should know these basic things.
Please, please hire someone who is experienced to run your server until you learn more.
Code:
chmod 755 /usr/local/directadmin/scripts/hostname.sh
or