I'm also very new with shaders, I only changed some a bit and tht's definitly the way I would recommend you learning it. Look for a shader that doesw something near to that what you want to do, and then modify it. Use the reference lists on the microsoft page to get an overview on what possible and whats not. I also earched a lot in web and wikipedia to get to know with all the special words (bumpmapping normalmap, blurring, RTT, etc.) This was also a help to understand the shadercodes, to know as much about the processes itself as possible. This makes you understand better why there are this are that inputs and outputs in the shader.