Materials are controlled using the Material Editor, which can be called up by pressing M.
|the Material Editor|
Once you've done this, you can still change the material within the Material Editor window and the object in the scene will automatically update. The slot and the object are now "linked".
Within each Material Slot there are a bunch of different options to change.
1. SHOW MAP IN VIEWPORT
This needs to be pressed in order for your "map" (the material) to be visible in 3DS max's viewports. If this isn't clicked, the object will just look textureless and grey (this is presumably for saving memory).
2. GO TO PARENT
This returns the window back to the main Material Slot when you're editing the diffuse properties or any other property within the material. Basically, whenever the Material Editor doesn't look like the one shown above, click this button to return to normal.
Makes the faces of the object invisible - only the edges will show up. A sort of "wireframe" mode.
Polygons (flat shapes). in 3DS Max default to one-sided - they are invisible from one direction. This makes them visible from both.
Removes all "smooth shading" from an object, making it look faceted.
Ambient colour is the colour of an object in shade. THIS WILL ONLY WORK IF YOU GO TO RENDERING > ENVIRONMENT AND CHANGE THE AMBIENT COLOUR TO GREY. Change the colour of these options by clicking the grey rectangle next to the name.
Diffuse is the colour an object is when it's in full light, so this is the main way of changing the colour of an object. Click the little square button to the right of this to add an image to the material - this will bring up the following list:
A good one to be aware of here is the "Checker" pattern, which is (as you'd guess) a black and white checkered grid. This is quite good as a default texture to see if your mapping results in much deformation.
The main option here is "Bitmap", which allows you to pick your own 2D image which will be applied to your object. Double click on Bitmap to choose an image.
Remember that if you try to put a Bitmap on an object, it won't show up in the viewport unless you press the "Show Standard Map in Viewport" button.
Once you've set the Specular colour, increase "Specular Level" to make it visible. Then, use a combination of "Glossiness" & "Soften" to get the right level you're after. The graph that appears might help to visualise this.
Self-illuminated objects are sources of light (they don't need light to shine on them, they just are lit constantly). The main reasons we might use this are to make an object constantly visible (making reference photos Self-illuminated means they'll always be visible even if they're in shadow) and to achieve a sort of "toon shading" look, because the lack of shadows makes an object look flat and cartoony.
This controls the opacity of an object - 100 is fully opaque, 0 is completely invisible. Opacity in 3DS max is a little funny for a couple of reasons, so it's best to render everything out at 100% opacity and then change it in the comping stage (in something like after effects).