How to put the cube into the side of the material and the texture of that cube?

I want this:

Into this:

I don’t get it. “how to put the cube into the side of the material and the texture of that cube” makes no sense.
Cubes have sides. They don’t "go into "sides.
Materials don’t have sides.
You don’t put cubes into textures.

Hey there @Super_Tuxon! Welcome to the community! I didn’t understand your requirements here. Are you find the cube in the content browser? The cube itself is likely the base engine cube.