What, how?
the magic shop will have a golden dubloon for sale, you throw the coin the fountain and then talk to the fairy, then you need to visit her a few days and always bring her fruits until she finally has enough magic and gifts you fairy dust (currently the dust can not be used), after you have collected the dust visit her again on the next day and offer her to come with you, the she is at your home but you are only able to speak to her in the morning