Before attempting to add a page(s), make sure you have been given permission to add pages by your book’s Admin. The Admin may not have given you permission to do so.
To add a page, go to Pages in the top-level toolbar.
Once there, click on the Pages flyout in the second-level toolbar.
Click on the New Page button.
This will allow you to specify how many pages you wish to add and where you want them added. Once you have entered what you want, press Add for the pages to be added to your book.
NOTE: You cannot add pages between two pages that are linked—they are treated as one page. If you wish to insert a page(s) between two linked pages, you must first unlink them and then add them.