I am trying to learn NMM and know that you need to have light next to dark. I cannot find anything to help me figure out this subject. i have looked at NMM videos and they do not answer this simple question.
A simple google search for iron cylinders will give you the basics for cylindrical leg and arm armour, spheres for rounded shoulder pads etc.
These can be used as starter points...it really then depends on how lifelike or stylised an approach you are taking.
There are also plenty of simple illustrated guides to zenithal lighting that will help with the principals and understanding how different volumes react to light sources.