How do I write a book?

This might seem like a really dumb question, but I've always enjoyed writing and I know I want to write a book. I've never written anything but short stories or poetry, though, and I'm not sure where to begin! I've been working on an outline but I get lost in the details, and I'm not sure what to do next. How do you get from having an idea to having an actual first draft?<br><br>People always talk about writer's block, too. How do you avoid that? And how do you actually write? Is it just sitting down and typing out a chapter every day, or is there something else?<br><br>[EDIT: I feel a bit like I'm being attacked. I'm not trying to do anything NaNoWriMo and I'm not trying to write a book in a month. I'm just trying to learn how to do it.]