The eBook Guide provides details on how to download/borrow an eBook.
If you only want to download a few pages or a chapter:
Locate the eBook and open it
The number of pages you can download varies from book to book, based on the total number of pages
In the menu options look for wording like 'save pages', 'print to PDF', 'print pages', 'chapter download'
Select the page range or chapter and save the pages/chapter to PDF
Note: Generally copyright rules state you can print or copy 10% of a book. Each book may have slightly different allowances and this will be shown on the opening page of the book