Simplest would be to grab the demo app (http://www.barneyb.com/barneyblog/projects/cf-groovy/) and fire it up. The examples are contrived, but you'll get the idea. Then start poking away at the Hibernate documentation.

CFGroovy can't replace CFSCRIPT completely, as you can't access CF built-ins from Groovy. Similarly, once you invoke a Groovy method from CF, you can't call back up to CF from the Groovy class. I've not found that to be much of a problem, however.

What should I learn first and where?

Thanks!