First, double check if the library has your textbook in an online format (ebook) by using the library's OneSearch. You can search by title, or ISBN#. Please note that not all books are available online.
After searching in OneSearch, and you find that the book is not available online but the library has a print (physical copy) on the shelf, you can
a) Make copies if you are located at one of the campuses that have the book. Making copies is free at all Chicago School campuses.
Or, if you not near a campus that owns a physical copy, you can:
b) Request a digital copy of one chapter. Make sure you are signed in, and then under "Get it" click on "Digital Chapter Request."
It usually takes anywhere from a day or two, or up to 7 days to get a chapter emailed to you, depending on staffing, or other factors.
Finally, make sure to contact your instructor to let them know your textbook has not arrived. They may be able to provide alternatives.