Here i given name demo of server you can choose any: Enter following cmd
Step 1: cd /etc/apache2/sites-available/
Step 2: sudo cp 000-default.conf demo.conf
Step 3: sudo a2ensite demo.conf
Step 4: sudo nano demo.conf
In step 4 add below lines in demo.conf file:-
ServerName demo.com
ServerAlias www.demo.com
Step 5: cd /etc/
Step 6: sudo nano hosts
Step 7: add 127.0.0.1 demo.com in the list.