Major trouble understanding structure

Hello,

This is my first time creating a Photoshop Plugin, and I am having a lot of
trouble understanding how to do it. I am using Microsoft MFC to create it. Does
anybody know of good references or sample code to look at? I simply don't get
how to create this!!!

I am trying to do a filter plugin that will let the user select a particular
color, and turn all other colour in the image to black and white.

MFC isn't a very good choice, as it's not portable.