This is for Winmugen only.
Mugen 1.00 users, this tut provably will not for you guys.
Assigning the song
Place your song in the Mugen/Sound folder, and follow these steps.
1 - Shorten the song name to one single word. Copy the song's name.
2 - Open your Stages folder and look for the Stage you want to assign to that specific character, and thus add the song to, then open the stage's .def (Definition notepad) file.
3 - Look for the following line.
bgmusic = sound/Rollin.mp3 < Add song here.
bgvolume = 255
Paste the name of the song you copied into the line directly after the bgmusic=.
Don't forget to add the folder path where the song is at, and add .mp3 after the song name.
Make sure bgvolume is set to 255. (Max volume)
4 - Save and it's done.
1 - All songs must be Mp3
2 - It's preferable that songs don't have any spaces in the names, and be as short as possible.
3 - Make sure you type .mp3 after typing the song name in the stage .def file.
Assigning the stage to the character.
Now that you have assigned a song to the stage, you can now proceed to assign them to the character.
Go to the select.def file, which is under the data folder.
Make sure it is the select.def you're currently using, and not a backup, or one that you may be using for another screenpack.
Under the [characters] section and after the character name, add the following line, like so:
...and that's it.
If you still get NO sound at all, go to this: link and download the plugins, then put them on your plugins folder.
It may be that you comp doesn't have the right plugins to play sound through mugen.
That should solve the problem.
Another method that I sometimes find, that if you re-adjust the sound acceleration on your computer, sometimes solves the problem. So try that too.
Since you have assigned the song to the stage using the stage.def method, you no longer need to add any extra lines in the select.def.
THIS IS THE BEST AND SIMPLER WAY TO ASSIGN BOTH A STAGE AND A SONG TO A CHARACTER.
Just do exactly as the tut explains, and if you still can't do it, then there's something wrong with you, and you need to learn to read and follow instructions.
One other thing you should check for is that if the music stops playing once it's finished, and wont repeat, go to the stage.def and look for the line:
Set the resetBg to 1 so the song replays and never stops.