Getting error while installing phpmyadmin to clean LEMP Stack Ubuntu 14.04

I created a droplet with LEMP app with Ubuntu 14.04.

After that I wanted to install phpmyadmin .

I ran these codes by following this tutorial: https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-phpmyadmin-with-nginx-on-an-ubuntu-14-04-server

sudo apt-get update
sudo apt-get install phpmyadmin

Then I got a prompt to choose which server I would like to configure; then I push the tab button skip this step.

And then… I got these error and stopped working.

apache2_switch_mpm Switch to prefork
 * Restarting web server apache2                                                AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
(98)Address already in use: AH00072: make_sock: could not bind to address [::]:80
(98)Address already in use: AH00072: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
AH00015: Unable to open logs
Action 'start' failed.
The Apache error log may have more information.

I tried and tried again but nothing happened. Could you please someone help me?