Write or type your full story on a single sheet of paper to use as your reference. Make sure you know where the pages will break.
Create a story board which is visual representation of the pages you are writing. Move the words around on the story board so you know where to place the illustration in your mock-up.
Count the number of pages in your story including the front cover and title page. Divide this number by two. You need one sheet of 8.5 x 11 inch paper for every two pages of your story.
Fold each sheet in half. Write the name of the story and your name on the first page. Fold the remaining sheets of paper in half and insert them inside the first folded sheet so it looks like a book.
Write the lines of the story on each page. Start the first line of the story on the right side of the first inside page.
Leave room at the top of each page for illustrations or draw illustration if you are an artist. Add page numbers to the bottom of the pages so the reader can see how the mock-up will look as a real book.