Lets get direct to the command what it means:
To edit hostname for the user , go to the command line ( Ctrl + Alt + T)  then use the following ommands.

sudo gedit /etc/hostname

In place of gedit you can use any text editor.

And, for hosts

sudo gedit /etc/hosts

which results

127.0.0.1 localhost
127.0.1.1 saggi
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Enjoy!