Your hostname can be anything you like. If this is just a local box, name it according to how you want to access it. However, if this box is on a network with a DNS server, then you can name it whatever you want.
For instance, my server is named "tookie". However, in DNS, it's "www.snaghosting.com" and "www.cleancode.org". If you log onto that box and run 'uname -h', you'll get back "tookie". Because that's its local name. Everyone using DNS to resolve the host name
www.cleancode.org will get the IP of tookie back.
So, if you're setting up a little web server just for your own use, name the box what you want to. You can add extra entries in the /etc/hosts file to accomidate what you want to access your web server with. For instance:
Then you can pull up your web browser and type in any one of those names and your web page will pull up from your local box.
If you're wanting other people to access this box over the internet and they will be accessing it via
www.mysite.com, then who ever you registered your domain name with, you'll need to go there and assign that domain name with your IP address. The, you can still call your box whatever you want. However, the people accessing it from over the internet will be hitting it by whatever you assigned in DNS.