How do I change the color of my plane?

I am using the free version of unity and I made a building but the walls (transformed cubes) and plane are the same color and when I start the game with the third-person controller, all I see is gray and it is difficult to navigate.

Drag and drop a different color texture onto the object, have a copy of my basic color textures to get started(see below, unzip then drag into your project), when you drag any of these onto the object it will create a material with this texture and the basic diffuse shader. :