To have a chapter of a physical book digitized, click on the digitization link within a record. (Make sure you are signed in first!)
The above link to Ebook Central will bring you to the Advanced Search page. With Advanced Search you can build and fine-tune your search of available ebooks.
Once you perform a search within Ebook Central, you will be brought to a list of results. From there you can refine your search or browse the search results. Clicking on a title or the "Table of Contents and More" symbol will bring you to more information about the title as well as a list of chapters.