What you need:Brawl Crate: https://github.com/soopercool101/BrawlCrate/releases
Im using my own menu since its already made to be easily editable: https://gamebanana.com/guis/34650
Hopefully by the end youll have a basic understanding and then you can work on your own custom menus.
Section 1: CSS (Character Selection Screen) [sc_selcharacter]You usually find this file in pf\menu2.
1.Changing the Colors on The BGDownload and Install Brawl Crate. Once done, open Brawl Crate to get this window:
Click File and Open, select the menu file:
Youll end up with this:
Now open misc data  by clicking + or double clicking, continue and open up 3d models and select the model shown here:
This is the menu BG. You can preview it by right clicking and selecting preview model:
A new window pops up, use the mousewheel or ctrl- to zoom out:
Now keep both windows open, expand the model tab, then materials, and select the material shown here:
Now go to the far right window and select Color0, youll see an arrow, click it:
Select a color, and select OK, Im going with this value myself:
Next to change the sky itself select this material and do the same thing:
And thats it! Save by clicking file save or ctrl+s on the main window.
Then test it:
Thats how you change the menu BG's colors.
2. Changing texturesFollow the steps in (1.) on downloading, installing and opening the menu in brawl crate.
Now open the menus tab until you reach this point in this model:
Here youll find all the textures, say you want to change the logo, you can find the logo here:
First view the texture resolutions here:
Dont worry about the format for now, but try to make your logo or textures in that same resolution if possible.
Right click the texture file and click replace:
Look for your texture or logo, and select it, this window will pop up:
As you can see, I selected one with wrong resolutions, to fix it, just place the correct resolution on the window, click apply and check if its still the same format as the original:
Then click ok, then save, proceed to change other textures if desired.
3. Removing Objects by CullingThere are 3 types of object removal. 2 of which just makes them invisible, Scale, culling, and deletion. Deletion on menus is kinda risky and scale will be touched in the animations sections once we reach it. Lets focus on culling for now.
Follow the steps on how to download and install Brawl Crate from step (1.) Open the menu file:
Touch any material, in this case "Icon", and expand it, select the reference to see what texture it actually is.
Now click the main material and head to the culling section:
This here determines which side of the model is culled(invisible) if you make it cullAll, it makes everything is invisible. In my opinion this is the safest way to hide something, although it doesnt cut MB size, it keeps it the same.
Lets go ahead and make the grids invisible too.
Thats it, save and test.
4. Transferring the BG onto other CSS'esFollow the steps in (1.) on downloading, installing and opening the menu in brawl crate.
If you want to transfer bg assets from one menu to another, this part of the guide is for you. We may thread in a bit of advanced levels to mod, so please be sure to check the past steps since they also help you learn to navigate Brawl Crates interface and needed functions. Here we are using my Sky tears menu BG, we are gonna move it on to another (Im using Legacys Vanilla menu). This will also teach you what the files are and how to replace them.
On the .pac please extract the following assets from the Sky Menu CSS.pac
This is the model, export as .mld0
This is the animation.
And all of these are the extra textures.
Thats all you need. Now on your own sc_character you are gonna replace things:
Replace this with the model you exported earlier.
Same with the CHR animation file.
As for the textures, replace those that where on the menu, making sure the settings stay the same as the "OG sky tear menu". These textures varies with each other, so make sure to double check that the formats and resolution are the same as in my menu.
And for new textures that are added to the menu:
Thats it, save and test! Thanks to DesiacX for recommending me to add this part!