Hi,
a few things to check:
1.) have you checked your logfile of the firefly server. Should be /opt/var/log/mt-daapd.log?
2.) have you started the Firefly Server after installing the software? Reboot would also start the server.
3.) Can you see your Firefly Server in iTunes? In order to see it in iTunes you need to configure iTunes to look for shared music.
If you have anything strange in your logfile, please post it. This gives the community a more detailed view on your system.
Kind regards
Jens