Start with Ruby itself. you need to understand the basics about programming. This book is awesome.
In parallel, you can study a little about databases, independent of vendor (MySQL, PostgreSQL, Oracle…) a little experience with SQL is necessary.
After that, take a good Ruby on Rails book, Ryan Bigg is maybe the coolest RoR writer, mainly for newbies like us.
With these books, you’ll be well guided to Web Development with Rails.
Ohhh, another tip is watch Railscasts from Ryan Bates. This guy comes every week with some awesome tutorials.