Where can you find hogwarts textbooks?

you wont find all of them . but one is for sale called "fantastic beasts and where to find them"

and also the book Hermione gave to harry for Christmas "Quiditch through the ages"

and the book Dumbledore left for Hermione in his will which the last book is solely based on . i would highly recommend you read this "tales of Beedle the bard"