There are 7 Harry Potter books in total, and the author is JK Rowling. The overall plot is the traditional one of good versus evil, and the context in which this battle is played out is at a school for young witches and wizards in England, where Harry Potter is a pupil. All the books are good, but it's probably a good idea to start with the first in the series, which is Harry Potter and the Philosopher's Stone since a) it's the shortest and b) it will set the scene and introduce the characters in anticipation of what happens in the following 6 books.