Best thing to do is go through the samples in the distro (samples/quickstarts). There are quite a few of them, covering different features.
The Getting Started guide is pretty "step by step" in its approach and should be able to get you to the point where you can run the other quickstarts and start to try to break off small pieces of what you want to accomplish.
Thanks for answering, I started coding the "hello_world_xxx" examples yesterday. I noticed there were more complex examples also so I hope they will do.
Still, I would love a book about JBossESB/Rules/jBPM though - now I guess I'll just have to spam the forum with questions about the examples ;)