Sorry, reading my comment back, I do sound flippant. Such was not my intent and I apologize. It's just that I thought a shader was something you used to give an object texture and the way Robynsveil used the term, it is more like a tutorial. The link she provided took me to a discussion way, way over my head. If I knew enough to follow that discussion I probably would never have had  to ask the question in the first place, that was where my remark about English came in. When I asked, I was looking for an answer like Basicwiz gave (step 1, Step 2...), not how it works in theory. Again, very, very sorry. I stand corrected and humiliated.