First of all, check that you have the correct required configuration.

1. If you haven't done it yet, download the latest version on the software.
2. Unpack te archive locally then upload all files on the destination server in the browsable directory for your project. (Tip: In case you have SSH access to the server, you can unpack the archive directly in the right place)
3. Give the web server write permissions to 'includes', 'pages/common', 'log' and 'classes/custom/dao' directories.
   
   If you are using FTP :CHMOD 777 includes
   CHMOD 777 pages/common
   CHMOD 777 log
   CHMOD 777 classes/custom/dao
   If you are using SSH :chmod -R 777 includes
   chmod -R 777 pages/common
   chmod -R 777 log
   chmod -R 777 class/custom/dao
4. You can now browse to your installation directory to launch the automated setup process.

Once setup is complete, set back protective permissions on the 'includes' directory.

If you are allowed to manage web server settings, add a new virtualhost targetting the '/pages/admin/' directory for the back-office, and ad as many virtualhosts as needed, all targetting the '/pages/public' directory, for each one of your application frontends.

If you are not allowed to manage server settings you should redirect back-office requests towards the '/pages/admin/' directory and front-ends requests towards the '/pages/public' directory with dedicated rewriting rules in a .htaccess file in the root directory of the application (URL rewriting has to be activated on the server).
Still if you can not manage server settings, it is crucial to protect the 'includes' directory from being accessible, once again with a dedicated htaccess directive.