This may actually apply to more than books, but this is the first time I've run into it.

I've created a new book. I can't seem to find the world art images for the book so I can place it in game. I tried copy/pasting Clutter\Books\Book02LowPoly02.nif into the World Art field, but it doesn't take input.

Clicking on Edit takes me to an empty directory. (C:\Users\mark\Documents\Clutter\Books\Book02MG03LowPoly.nif refers to a directory that does not exist blah blah blah)

How do I access the art? Are there some files I need to decompress or something?

You'll need to unpack the bsa's, which contain the art. Or, to save time, you can simply change the ID on an existing book to create a new one.

Ok, that was going to be my next step, but I was afraid to mess with the ID's on existing stuff.

Thanks!