The main window is the mini file manager, which show only .mp3 and .wav files. If you want to add chant in FM09, double-click on file, choose "player" or "team", and enter ID (you can find all Ids in data editor, or simply tick "show unique Ids" in FM preferences).
FMSC will add needed line in match_sounds.cfg
Author - svsrus
this information is from si forums
if you manage to get it to work please make a pack for fmf.
Uploaded by Adamjigey
credits to: svsrus for making this