If you’re looking for a free rebol ebook and type this on Google, you won’t find any, whereas there is one excellent here, so to boost it on the search engine, I have created this post.
It’s a gentle but rather complete course to Rebol language which will give you a good background to understand other books like the one from Olivier Auverlot and Peter Wood or tutorials on rebol tutorial or elsewhere like the excellent musiclessonz now re-bol.com.
admin: 
MIKE Husemann: 
Thank you for the link to the http://musiclessonz.com tutorial. Just to keep things current, the most up to date version of that tutorial is now at http://re-bol.com. That page is much improved over the original beginner’s tutorial.
You’re welcome. Will also add Lunarpages as you mentionned them by email as rebol hosting provider.