Introduction to HLSL shaders

Simple Pixel shader tutorial

Programming Vertex shaders

Programming Pixel shaders

If you are new to 3d gamestudio or games development (from scratch not just MODS). Then I suggest that you dont get into shaders right away. I still havent got my head around shaders because they are very complicated and require alot of maths (something Im not good at ). I suggest you learn how to do the basics first before you try to learn shaders. After all they are just eye candy and dont really add anything of gameplay value