Log into your account at chatbooks.com and click into your bookshelf
Click on the subscription you'd like to edit
Click on the Chatbook you'd like to add a text page to
Click the blue plus sign and then click "Add text page"
Add your text and click "Done"
Your text page is now added to your Chatbook. To learn how to move it within your book, click here.
You can also add a text page to your Monthbooks/Minis on the Chatbooks app. Learn how to do this here.