Beginner: assigning texture to part of GameObject

I have a GameObject originated from a FBX file - representing a 3D object. It is combined from several 3D parts. I have materials (2D textures imported from JPG) for these parts. In Unity editor I am able to drag&drop these materials onto appropriate parts. But I can't find a way how to do this in a script.

Following code

   Texture2D tex = (Texture2D)Resources.Load("Materials/xxx", typeof(Texture2D));
   go.renderer.material.mainTexture = tex;

set the texture to the GameObject itself and not to the appropriate part.

What I'm missing is what are these parts in context of Unity and hot to access them. Thanks

So, you are seeing the parts as children of a main game object? To access kids, take a look at Transform.Find in the manual: Ex (this is C#):

Transform arm = transform.Find("arm");
Transform foot = transform.Find("body/leg/foot");

arm.renderer.material.color =; // null exception means it was spelled wrong, above

GameObjects don't have a Find, so if your GO is one, I think: `go.transform.Find(.....)`