Can someone explain to me how to get started developing Ruby on Rails?
I would recommending getting the following book:
also, home in on the RubyonRails web site.
The Rubyonrails documentation page is helpful.
I tutorial (Rolling with Ruby on Rails) listed there is great. It is what I did first to give me an overview of what Rails was about and to see if it would do what i wanted.
( The wiki is not the best ever (get to it via 'community'), but there is some good stuff there.)
The next thing I realised was that I needed to understand the distinction between what is Rails and what is Ruby so I could make sense of the code. I went through the online Ruby book (pickaxe):
You don't need to understand it all on first read, but without grasping the Ruby basics, you will not make sense of Rails.
Also, you need to find your way around the Rails API.
This takes a lot of getting into. Understand MVC from the tutorial, then understand which modules relate to which part of the Framework, (eg. ActiveRecord for the Model etc). The API is hard to get into, it has examples, but often in an adjacent or similar method. Getting to understand the parameters and options takes a while. But once you home in on the method you want, you can nearly always google an example. Particularly on this group.
Finally, for me - when I was convinced I wanted to really get into Rails (and I love it), I bought the Agile book already referenced by chirag. It really does cover the vast majority of what you want to know and is well presented. The pdf download is good value.