Texturing part of an object

Lets say I made a cube in sketchup and within each face there is a 2d square, once imported into unity, I click the cube, I can see the 2d square on the a face of the cube.

How do I add texture to just that part of the mesh?

Thanks!

Can’t Get you properly But if you want to change the Texture then

public gameobject Cube;//assign this in inspectoer

public Texture2d texture;//assign in inspector (The image or texture you want to apply )

Cube.renderer.material.mainTexture = myTexture;