We use textures and materials to paint on the surface of a 3D model, but there is a difference between textures and materials.
Textures are images. A PNG or a JPEG can serve as a texture. For example, you can find a high-quality image of concrete on the internet or take one yourself and import it in 3D Studio Max as a texture.
A material will use a texture or multiple textures as parameters. They control the color of the object, how reflective a surface is.
Press M on your keyboard. The Material Editor will appear on your screen. Select one of the empy slots (spheres) - that's where your material will be created. You'll see parameters for maps such as Diffuse, Specular Levels, Glossiness, Normal (Bump) or Displacement maps.
A Diffuse map defines the color or pattern of the object. It paints that data on the 3D model.
A Specular map degines a surface's shinniness and highlight color. The higher the specular levels, the shinier the sufrace will appear. A surface of a dry stone or cotton fabric will have a darker specular map, while the surface of a metal object will have a ligher specular map.
A Gloss or Roughness map controls how sharp reflections are.
Each color on the diffuse map represents a different axis of direction which can help the computer understand different shapes. A Normal Map represents small and medium bumps in your image. For larger bumps, a Displacement map should be used: ground, rocks, cliffs.
Now, you can download the maps I have prepared and replace the maps in the Material Editor. Once this is done, click on your material, drag it and drop it on your 3D model. The model is now textured!