Please help me I have an ar (action replay) if it helps. How do you fill..

Question for Pokemon Ruby

Please help me I have an ar (action replay) if it helps. How do you fill up the painting up the top of the art museam it is driving me mad. I have been told you go round to other peoples houses in the game and look at there paintings and tell him about it. If that is true plz tell me where these peoples houses are if not tell me how.

Thank you so much.