The problem with dialogue.

The whole point of this blog is that I am using it as an aid to writing a book. It’s going swimmingly. I have a plot laid out, and am slowly but surely creating a whole new world for it to take place in. I am getting to know what my main characters will be like, and how they will drive the plot forward. But that leads me straight into my first (and biggest) stumbling block. They are, at some point, going to have to talk to each other.