Your missing one important point. The sound file MUST be in .wav format. When you upload it, the Toribash server won't change it for you. Additionally, the absolute maximum time limit for said .wav format file is 5 seconds. Anything longer then 5 seconds and it will either not upload, or won't play in-game. I haven't uploaded my own sound yet, so I am unsure of what will happen. Finally add the fact that the item will ONLY play at the beginning of the match, only when you are playing. So if you are in the queue list your sound will not play. And fix your link :3.

Other then that, good tutorial.