Quiet Magician
Superstar
HTML/CSS isn't really a programming language. They are mark-up languages, and thus, relatively easy to learn. I would give HTML/CSS a month or two to learn in depth if you go hard with them. HTML is very easy to learn. CSS isn't particularly difficult either, but it can have a ton of details which can throw you off. If you want to get started learning HTML/CSS, go to codecademy.com and go through the HTML/CSS track. Then start working your way through some books.HeadFirst HTML/CSS is a great one for starting off. When you're ready to get advanced with the CSS, get CSS the Missing Manual.
Javascript is something I'm still in the process of really learning. The basic syntax and doing the basics like loops, conditionals, etc. are simple, but where Javascript gets difficult is understanding concepts like closures and the more advanced things. Learning a full language like Javascript or PHP will take several months to get the hang of and years to master, so don't rush the process. IF you're going to do back-end development and you like what you've done with Ruby on Rails, don't worry about using PHP, and stick with RoR.
By any chance are you a developer?