the animation is not part of the WAD editing.
the WAD is like a zip or rar package which contains files to extract on internal NAND's different paths. it also contains a banner animation file which can be replaced with another banner animation file.
it doesn't define the animation.
The animation file (00000000.app in the wad) contains another set of sub-files that you have to extract and repack each time you want to test your animation, one for the picture, one for the script defining how the pictures are moving, the effects, etc.
What you are looking for, is a banner editor.
it was suggested to make a visual editor long time ago, but has never been made because it requires a lot of time to make one.
instead, you have to edit all the files manually and repack them into a .app file, then repack it into a wad file.
There is a tutorial by SifJar for banner animation edition and creation here :
https://gbatemp.net/threads/wii-banner-creation-editing-guide.291151/
Too bad, the pictures are dead, and the "easier to navigate" mirror site is dead too.
To make things easier and test your animated banner, you don't need to repack into a wad each time and reinstall the wad on Wii (and risk a brick of your system menu !).
you could repack the wad and install it on Neek to prevent bricking your SysNAND, but it's a lot of steps to repack the wad, reinstall it, etc.
instead you can use a banner animation player :
there is one in USB loaders (rename the banner with titleID of a game you have on your USB, and the loader will play it).
or use the Wii banner player app from Dimok (I don't have the link yet... searching now), I think it's a homebrew, not a PC app.
Edit :
Actually, there are two version:
Homebrew : Wii System Menu Player
https://gbatemp.net/threads/wii-system-menu-player.325976/
http://wiibrew.org/wiki/WiiSystemMenuPlayer
can play .app and .bnr from SD file
Windows app : Wii Banner Player
https://code.google.com/archive/p/wii-banner-player/downloads
I never used it, I don't know how compatible it is with existing banners.
If you want best result, use the USBLoaderGX banner layout and put your .bnr (00000000.app renamed to TitleID.bnr) on your cache banner folder.
or the homebrew I posted above.
