I downloaded a Megaman stage "Gate Laboratory V3.0 (Megaman X6)"
I want to replace a custom stage I made in Brawl with this one. I can't find the tutorial for this.
What folders do I create? Icons, stages, songs, etc.

I found some information on this but it's really confusing me.

There's a file named "st_customXX.rel". I opened this with the hex editor and the values are
"38 A5 00 00 38 80 00 00"

There's also stage files "STGFINAL - Gate.pac", "STGFINAL - Sigma.pac".
There's music and icons but not worried about that yet.
In my Brawl, I saved a bunch of custom maps. How do I replace one of those maps?

What's the difference between these two files?

I downloaded some files that only have a PAC file...will this work alone?

F:\private\wii\app\RSBE01\pf\Fighter\peach

FitPeach02.pac
FitPeach02.pcs

Now how do I get brawl to load this new data?