As said I have never read the Harry Potter books but in the case that I do in what order should I read them in?
The most important books in the Harry Potter series are the seven books of the main storyline. They should be read in order, as each builds upon the previous ones.
- Harry Potter and the Philosopher's Stone (aka Harry Potter and the Sorcerer's Stone in the USA)
- Harry Potter and the Chamber of Secrets
- Harry Potter and the Prisoner of Azkaban
- Harry Potter and the Goblet of Fire
- Harry Potter and the Order of the Phoenix
- Harry Potter and the Half-Blood Prince
- Harry Potter and the Deathly Hallows
Then there are additional works, often originally written for charity. These add some colour and background to the story, but are not necessary. A number of them are named after a fictional counterpart in the Harry Potter universe. Those can be read after their first mention in the books, or after the main series. If read before the main series, they might contain spoilers.
- Fantastic Beasts and Where to Find Them (not to be confused with the film series of the same title)
- Quidditch Through the Ages
- The Tales of Beedle the Bard
- Hogwarts: An Incomplete and Unreliable Guide (e-book)
- Short Stories from Hogwarts of Power, Politics and Pesky Poltergeists (e-book)
- Short Stories from Hogwarts of Heroism, Hardship and Dangerous Hobbies (e-book)
There also is an unnamed Harry Potter short story that takes place before the main series. It has never been published and the manuscript, which was sold at an auction for charity, has been stolen.
The odd one out is Harry Potter and the Cursed Child, which is a play of which the script is available as a book. It is a sequel to the main stories, but retcons parts of them. Reception within the fan community was mixed, with some regarding it almost as fan fiction. You may want to skip it altogether.
Then there's the Fantastic Beasts series of films, of which the screenplays have been published as books. Of course, not to be confused with the earlier book of the same name.