Radria requires a working Web Server with PHP.
If you do not have a web hosting account or want to use Radria on you local computer for offline work, you can install a LAMPP (Linux, Apache, MySQL, PHP) server on your personal computer.
The installation is most of the time easy and painless.
See the apachefriends.org web site for installation instructions and support.
XAMP installs itself in /opt/lampp folder, start xampp with /opt/lampp/lampp start as root then copy the radria file in /opt/lampp/htdocs and go to http://localhost/ with your web browser.