If you're here, it's probably because someone, somewhere, thinks you need to learn to play. Now, usually, people who say "L2P" are talking about little mechanical quirks of a given game, or effective use of particular abilities. No, it's not that. This is about learning to play. You know, have fun doing stuff. Like what kids do. I'm mostly framing this in terms of Massively Multiplayer Online games (MMOs), but really, this applies to everything.
You may not have noticed, but a kid can have more fun with a stack of unmarked wooden blocks than most MMO players can have with multi-million dollar game software. This is because kids know how to play. You probably don't. You can learn.
You might start out with Why play?, an overview of why you might want to play, as opposed to being all boring and serious.