I'm hesitant to recommend this because it's a translation of a book written for another language, and by an author that I don't find myself often in agreement with. However, I do like the sentiment of this book and it being available online for free is a great thing.
As the link says, it's Learn Ruby the Hard Way. It's not being sarcastic. There's a lot of books out there that claim to offer quicksilver solutions to picking up a language. And a vast majority of them are worthless. There is no easy way to pick up a language. Especially your first one. And this book takes the opinionated position that the best way to learn is by writing code and observing the consequences. So it's a very hands on approach where the intricacies of the language and underlying implementation details are left to the viewer to explore at their leisure, but trial and error with emphasis on observation by the user is the real vehicle by which reading this book may help you learn Ruby.