First, I am new to this and couldn't find anything anything on this topic with a quick search so I hope this isn't the gazillianth time this has been asked...

I have one domain but I want to create a website whose root is not that domain's home page. I want to save my domain homepage for something and this other website is completely different with a different theme and everything.

Is there a way to do that?

THanks in advance,
Kier

Yes you can setup a sub domain. If your host has a c_panel you should be able to login to it and find the area where you can add it.