[HELP]Adding a new skin with OpenIV (ytd files)

[Mr_Kerr]

Hey guys,
I'm currently trying to add a new skin to the game. But I think I've got a problem. The only texture I made is the diff_000_a_whi one. But I just saw that I need two more. Let's for example take the Iron Man skin. There is the normal-looking diff_000_a_whi texture, but also a blue version of the main texture called (head_)normal_000 and a very bright one called (head_)spec_000. What do I need them for? And how do I create these textures for my own main texture?

(I am talking about the textures you can look at in the .ytd file with OpenIV)