a little quest, keiko: have i rename the new file, or i can just put it in the folder!?
I don't have access to the directory folder at this moment so I'm not sure how accurate my instructions will be, but if I remember correctly, there should be a .txt document of some type among the .ogg files. Open that document and you should find a playlist listing of every file in order that they will play in the game. As long as the files in the folder match the playlist in the document, they should work.
The simple way to do it would be just to overwrite the existing file with your music file but keep the name the same. I hope this helps