Is there a tutorial on changing the CAS background?

Hey taraalex !

I am not sure of an exact tutorial, but I can make one for you! , I simply used LumiaLoverSims variations HERE 
I recommend the solid colors as they are easiest to manipulate. 

1) Download which ever color or type that you want and place it somewhere you can find it. LumiaLover's post has some instructions as well. I recommend putting the folder into your Sims 4 Mods folder and just take out the file named like this: solid_white.package, for this is the actual file you will be editing.

2) Open up the studio and click on My Projects.  IMAGE

3) Find where you placed the file, select it and click Open.  IMAGE

4) You'll see this screen, and all you need to do is click the Export button.  IMAGE

5) Name it something you'll remember and then click save.  IMAGE

6) Next open the .dds image into your preferred editor and make sure to have Load Mipmaps un checked, I'm using GIMP.  IMAGE

7) Then add whatever changes you would like to the image, just make sure not to resize it or it will not work in-game. So keep the ratio: 200x200. IMAGE

8) To Export the image as a .dds, and name it as something, then click export. IMAGE
MAKE SURE when exporting that you make the compression: BC3/DTX5 and to Generate Mipmaps.  IMAGE

9) Import the .dds file into the Studio and then see how it looks and if you like it, click save.  IMAGE 

10) Place the file into your Sims 4 Mods folder and open your game, and it should be showing up!    
If you use a design and not just a solid color it may take a few tries to get it to look right!
Use LumiaLovers patterned version for refrence.

I hope this helps you some! If you have any questions or get confused at any point, don't hesitate to ask! 

wow this is a great idea thank you.

CAn someone please help me?? I recolored some shirts from the game and I want to share them and i dont know how. I'm still learning how to create or recolor and even posting up here please help.