OK so I'm on this part of the setup:

" After the installation has completed, add phpmyadmin to the apache configuration.
sudo nano /etc/apache2/apache2.conf

Add the phpmyadmin config to the file.

Include /etc/phpmyadmin/apache.conf "

...so I type sudo nano /etc/apache2/apache2.conf into the command line, it opens up a file. With nowhere to write that next command into

How am I supposed to add that in?

Whenever I open up ipname/phpmyadmin/ I get a 404 message

also whenever I restart apache I get this message:

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