If you are interested, RubyLearning offers a course on FXRuby and Shoes. Actually, the Shoes course is being conducted currently.
Probably the easiest is Shoes. As an assistant teacher at RubyLearning, I hope that we will have better courses for learners.
Some people got stuck in installing FXRuby. But Shoes has an installer for any platforms (Windows, Mac and Linux).
