Edited anthologies are book-length texts that include a set of essays or articles by a variety of authors. Monographs are a book-length text (not a collection of essays or articles). You can't always tell from the record in the catalog whether a book is an edited volume or not--you may need to actually look at the physical book or go into the ebook to figure it out. If a book is written by one or two authors, it is considered a monograph. If the book contains chapters or essays by a bunch of different authors, that is an anthology.
If you would like to browse in the stacks for books about Native Americans, you will find many of them located in the following call number area:
E75-99 Indians of North America