Umm...you know when you go in the Chateu, there're two staircases? Go up any of them, and enter the room at the top in the middle, if you want to see the girl, you go to the room with the painting, the one next to the last room way at the right. You'll see her in the other room soon enough.
If you want to come across a wild genger, you'll need Emerald, Ruby/Sapphire, or FireRed/LeafGreen in the gameboy slot of your DS.