Nano+1602 LCD+Catalex serial MP3 player

I am trying to update an earlier project fro creating a SD card based replacement for tape players in 8-bit home computers. Here
I have added a Catalex Serial MP3 player with built in SDCard.Can be found here.

I have everything up and running very basically at the moment but I need to be able to retrieve the filenames and display them on the LCD to make it easy to select the file you want. Does anyone have any idea how to do this with this particular card?