You should be able to use your user 'ray' in ftp. But 'ray' will be locked to his home directory so can not access the files of user 'rgc'.
With regards to phpadmin, I assume that that is still installed in /var/www and therefore no longer accessible.
What I suggest is to configure (another) virtual hosts. To do so, make a copy of your /etc/apache2/sites-available/default
Next modify the phpmyadmin file that you just created. The below example is based on the very original default file, not the one you modified.
sudo cp /etc/apache2/sites-available/default /etc/apache2/sites-available/phpmyadmin
You also need to create an entry in /etc/hosts for this new website; add the red line below. You need root privileges to edit the file.
Options Indexes FollowSymLinks MultiViews
allow from all
ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
Allow from all
# Possible values include: debug, info, notice, warn, error, crit,
# alert, emerg.
CustomLog /var/log/apache2/access.log combined
Alias /doc/ "/usr/share/doc/"
Options Indexes MultiViews FollowSymLinks
Deny from all
Allow from 127.0.0.0/255.0.0.0 ::1/128
Next issue the following 2 commands; the first one enables the new site on your system and the second one is obvious (I guess)
# The following lines are desirable for IPv6 capable hosts
::1 localhost ip6-localhost ip6-loopback
Next you can use a browser to access the sites
sudo a2ensite phpmyadmin
sudo service apache2 restart
http://localhost will give you the site that we created earlier (in your home directory)
http://phpmyadmin will give you phpmyadmin located in /var/www/phpmyadmin.
Virtual hosts is the normal way to allow one webserver to serve different websites (including different domains and subdomains).