Ah. I'm not sure how to get the music though
Ever the question.
Things I normally do.
So start by exploding it into the component files (not sure what we are suggesting these days but
https://code.google.com/archive/p/showmiiwads/downloads might do).
Anyway once you have it down to individual files you have various things to look at
File sizes. Music tends to be larger than next to nothing but might also not be that large as these things go.
File names
Folder names
File extensions. Nobody likes making file formats from scratch so they will use those provided by others (
https://wiibrew.org/wiki/Data_Containers http://wiki.tockdom.com/wiki/Custom_Music https://wiki.multimedia.cx/index.php?title=Category:Game_Formats http://wiki.xentax.com/index.php/Game_File_Format_Central ). As mentioned above there are ones that are used by multiple formats (.bin being short for binary, .dat being usually short for data, .arc presumably being archive though there is a common archive format in Nintendo consoles with that extension and more you can learn as time goes on)
Magic stamps. When you open a file in a hex editor then many a file format maker has a little indicator (either a run of hex, a run of text or something similar) that identifies the file as being of a given type.
Elimination based on previous -- if there is a folder/file name/extension saying graphics then chances are it is to do with that.
These get a lot of people most places.
After this you can start fiddling with files -- if you swap two files around and suddenly the music has changed or broken then chances are one of those files is your music. Related to this is corruption wherein you change parts of the ROM and then see what changes in the game proper.
The most reliable way, but also one that takes you learning a more speciality type of programming (see assembly) is tracing. Here you want an emulator with a debugger option (not sure what Dolphin is doing these days here) and you do things like
https://www.romhacking.net/documents/361/ (it is for the GBA and for a command line thing but eh) to follow it back up from something you can see it having an effect on back up to where the console formulates the command to grab the data from the disc/ROM/SD card/internet/... and thus precisely where to look and how it is treated by the hardware after that. Some systems have slightly lesser versions like compression logging (the GBA for instance has compression functions in the BIOS, if a game calls them and thus notes where it is looking, what format it is using and how much of it there is then you have a nice shining light saying something is here, might not be what you want but almost invariably will be something), and pointer inference is a thing too in some systems (though less useful on the Wii. On systems where it is then you might find what look like obvious pointers, little things that indicate the location of other data that programs use to locate things, then something will be at the end of it).