phppgadmin is installed in /usr/share/phppgadmin. You will need to create a site file in /etc/apache2/sites-available and enable it in order to access phppgadmin. You will also have to set up dns accordingly. The file should look something like this

<VirtualHost> *:80>
    ServerName pgadmin.caa.intrasec.net Redirect "/"
    https://pgadmin.caa.intrasec.net
</VirtualHost>
<IfModule mod_ssl.c>
    <VirtualHost _default_:443>
        Servername pgadmin.caa.intrasec.net
        ServerAdmin tim@jtek.co.uk
        DocumentRoot /usr/share/phppgadmin
        ErrorLog ${APACHE_LOG_DIR}/error.log
        CustomLog ${APACHE_LOG_DIR}/access.log combined
        SSLEngine on
        SSLCertificateFile /etc/ssl/certs/mail-caa.pem
        SSLCertificateKeyFile /etc/ssl/private/mail-caa.key
        <FilesMatch "\.(cgi|shtml|phtml|php)$">
            SSLOptions +StdEnvVars
        </FilesMatch>
        <Directory /usr/lib/cgi-bin>
            SSLOptions +StdEnvVars
            DirectoryIndex index.php index.html
            AllowOverride None
            Require all granted
            AcceptPathInfo On
        </Directory>
        <Location "/">
            Require all granted
        </Location>
        BrowserMatch "MSIE [2-6]" \     nokeepalive ssl-unclean-shutdown \ downgrade-1.0 force-response-1.0
        BrowserMatch "MSIE [17-9]" ssl-unclean-shutdown
    </VirtualHost>
</IfModule>

You will need to change the server name, SSLCertificateFile, SSLCertificateKeyFile and Redirect to match your configuration.

Don’t forget that the file name needs to end in “.conf” otherwise the “a2ensite” script will not work.  If you installed the Debian packaged version then you will also need to disable the phppgadmin conf that it automatically creates:

#a2disconf phppgadmin

You might want to create a superuser that can log on to phppgadmin. To do so run

#createuser NewUserName -U postgres -DRsP

Note that for security reasons phppgadmin expressly forbids the built in postgres user from logging on.