Check your library's online catalog to see if your textbook is available at the library. A textbook will be listed in the catalog just like any other book.
Most public libraries do not have textbooks available. College and university libraries have some textbooks, but do not purchase every textbook each semester. If your school library does have your textbook, it will probably be on reserve and you will be able to check it out for a limited time period (frequently 2 hours).