Baiss -
I looked at this package and, frankly, it does not make that much sense to me either. But then I find that when Anjo puts things in, be can often be ... concise, shall we say ... in how he documents things. I could probably buy and read through the doc for JFreeChart, but I have not done that yet.
I put a new Example project in Wonder. It is Examples/Misc/ERComponentTour. There is, after all, nothing analogous to the D2WComponentTour example and there are lots of non-D2W components in Wonder. The first (and presently only) page in that app is for "ERPCategoryChart & ERPPieChart." And there is no ERPPieChart yet. And the examples there are probably not the smartest. It certainly seems that for the AreaChart and WaterfallChart, this dataset does not make sense. But this is the first version, so it is obviously better than what was there before. And anyone who wants to show better examples of these components is certainly welcome to do so.
This example does show a minimal usage of the ERPCategoryChart. Let me know if this helps at all. Or, if it does not, what would be needed to make it make more sense? Let me know what you end up figuring out and I can probably use that to improve the example.
cheers - ray