I wrote ... et j'ai achetée ...un beau centre etc because there is a female narrator, but you corrected this to acheté. May I ask what I did wrong?

When the passé composé is formed using avoir (as is the case here), you always use the male form of the participle. It is only when using a form of être that you accord the participle to the subject.

Marcel a acheté une nouvelle voiture. Anne a acheté une nouvelle voiture.

Marcel est venu nous voir. Anne est venue nous voir.

Of course!  Thank you.  

Salut Hilde !

Whether the narrator is female or male, avoir + participe passé will just end in é in -er verbs. A scenario when the acheté becomes achetée is when you are referring back to something in the form of a Direct Object Pronoun.

Example:

A: As-tu acheté la fleur ?

B: Oui, je l'ai achetée. (achetée because the l' refers to the flower, a feminine noun)

I hope that helped you understand!

Bonne continuation !