question for you writer types

I have an interest (extremely unlikely to realize at the moment, but nonetheless, it is there) in writing a book about certain formative events in the history of one of Frank Herbert's (non-Dune) characters. Given that his son is milking the living shit out of the Dune universe, what exactly would i need to do were i to actually write this book and want to publish it?

question for you writer types

I have an interest (extremely unlikely to realize at the moment, but nonetheless, it is there) in writing a book about certain formative events in the history of one of Frank Herbert's (non-Dune) characters. Given that his son is milking the living shit out of the Dune universe, what exactly would i need to do were i to actually write this book and want to publish it?