There are some tutorials on YouTube that cover using Ruby with the RPG Maker series, so these may be of interest to you. If you want to learn Ruby for use with RPG Maker, this may well be the way to go. Alternatively, there are a set of general Ruby tutorials on there by SapphireSteel (there is an accompanying free ebook with the series) that may help you. I've not tried Ruby, but these were recommended to me as being a good starting point should I ever want to get in to it.
If you do look up the SapphireSteel tutorials, would you post back some feedback on how you found them?