Use the book to help guide your writing style. One of the primary features of an academic book is that it will give you an example of academic writing, which is very different from journalistic or other forms of writing. If you are unsure about your English, or are not used to writing a college essay, your English textbook can be a valuable resource. The more you read, the more confident you will become in your writing ability.
Use the book to help guide you with references. Often, citing within a college essay for the first time takes as long as writing the essay itself. Often, English courses require papers to be written in MLA style. Check with your professor's requirements, and then use the MLA style guide that can be found in many textbooks.
Read the book and make notes as you go. If you have been given the book for an English essay, read through the chapters you have been asked to read and note or highlight important areas. Pause at the end of each chapter and think about what has taken place. This will allow you to form a mental map of the narrative, and to form a basic idea of interesting and relevant themes.
Use the reference list or bibliography in the book to help you find other books to read. For example, if your English book is a book of literary criticism, look for bibliographical references of feminist literary criticism. Starting with one book will allow you to flesh out a reading list, and give you an idea of what other books you should read.
Look at the biography of the author on the sleeve or on the inside page. This will allow you to gain an insight into the context in which it was written. If you are reading a fiction book, knowing about the life of the author can be as revealing as the text itself. Studying "Middlemarch" is a very different exercise when you know that George Eliot is a woman. Gain as much contextual knowledge as you can.