You need to put these files on the server.
On yours, the easiest way, is put them in their own folder, under the Shared Folders. Them remote via RDP into the server, so you are at the server desktop. From there, open Windows Explorer and copy the three files from the above folder, to:
C:Program FilesFirefly Media Serveradmin-root.
After that, you should be all OK. You can acess your server music via the address: http://server:9999/Fireplay.html. (Replacing the word ‘server’ with the name you’ve given your own server).