A picture is worth a thousand words
Sometimes it is much easier to learn by watching and listening to an explanation, so Richard Bateman (the project manager) has put together a short video tutorial to help get you started.
This tutorial was created on Mac; most of the concepts are going to be the same, except for install and the compiler used.
Creating the project
Building and installing the plugin
Looking at the project files
Adding a JSAPI Method
Adding a JSAPI Property
Also covers accessing the plugin object from your JSAPI object, using PARAM tags, and customizing generated files.