It's open source - i'm not sure what you mean by "can we write class in class"
check out www.ruby-lang.org/en/about/
something that may be helpful for you to understand is that Ruby is the language (created by Yukihiro "matz" Matsumoto - www.ruby-lang.org) and that Rails is a web application framework (extracted from the Basecamp project by David Heinemeier Hansson at 37 Signals) that utilizes that language.
I, also, am quite new and would recommend the book "Agile Web Development with Rails" - http://www.pragmaticprogrammer.com/titles/rails/index.html - to help you get started.
Dilip Bv wrote: