A start point depends heavily on how you learn best. If you prefer to read up and do things the academic way, there are several tutorials around the internet which will "school" you through basic programming, gradually introducing more complicated concepts as you go.
If, however, you learn better by
doing, then grab a copy of
VC++EE (free). Follow the [ame=http://www.youtube.com/watch?v=VBRLkN__YIo]video on setting the compiler up for Orbiter addons[/ame], and take a peek at some of the sample code in orbitersdk/samples. I recommend for vessel modules to start by taking a look at the ShuttlePB code - change some things, see what happens, break it, change it, fix it, et cetera.
Basic understanding of programming helps a lot, which is where the book that you have will help a little. C is the language to learn, since C++ extends it and a lot of other languages are of a similar style. You don't need to learn it all at once, though - just the basic concepts will get you started - what is a variable, how do I modify them, what are they useful for, what's a pointer do, how do I reference them - what does * and & mean and what's the difference, et cetera.
I wouldn't start with the DGIV modification, partly because it's a complicated vessel, but also because it's closed-source, so the only way you'll be able to add a light via code would be to hack the DLL to add it in. There are non-code solutions for that - try creating a simple invisible "spotlight" vessel and attaching it to the front via UCD, code it to accept a keypress to turn the light on and off and bingo, docking light.
