If you visit that link to the turtorials again, it's #4 that you want to understand.
To do what you want is called an ADD-ON domain and not to be confused with a Sub-Domain. Add-on Domain names have to be purchased from a registra (like Voda Host) and "pointed" to the Add-on Domain server which will be the same as your Main Account Server.
It's ALL in the Tutorials. When you finally get to use the cPanel to install the Ad-On, read the instructions and the Bold Note there.
Good luck with it, it's not hard.