Let's add a new chapter. To do this, create a new .txt file in your book's manuscript folder.
Type this in the new file you have created:
# Chapter 4
It was a **bold** and *italic* night!
Save the change, and name your new file chapter4.txt. Making sure to save this new file in the manuscript folder for your book.
Next, you need to tell Leanpub's book generators you want to include this file in the book, the next time you create a preview.
To do this, add your new file to the list you will find in the Book.txt file in your book's manuscript folder.
(Book.txt is just a list of the files you want to include in your book, in the order you want them to be included.)
Open the Book.txt file with your text editor. If you're just getting started, right now the contents of Book.txt will look like this:
chapter1.txt
chapter2.txt
chapter3.txt
To add your new chapter to your book, type chapter4.txt on a new line and save the change. Now the contents of Book.txt will look like this:
chapter1.txt
chapter2.txt
chapter3.txt
chapter4.txt
Save the change you made to the Book.txt file. Then, go back to the Preview page for your book, and make a new Preview. Now, you will see Chapter 4 in your book.