This is a very simple task, however many linux server newbies will be hard pressed to figure it out on their own.
First, edit your /etc/hosts file with vi /etc/hosts
Second, change any lines such as:
127.0.0.1  new.server.com server localhost.localdomain localhost
Simple change the “new.server.com server” part to a valid hostname, Such as: your.host.com yourhost.
Then save the file with :wq command.
If everything was configured correctly, set the new hostname with the following command:
# hostname your.host.com
and everything should be good!