Instructions
Turn on your "Pokemon SoulSilver" game. Hit "X" to pull up the menu. Press "A" on the on the icon shaped like a photo ID card. Look beside "IDno" for your number.
Navigate to the Filb.de website. Select "Spiele" from the top header, then click on the link "Pokemon HG/SS." Click on the "Pokemon Geheimwort-Generator" link.
Select "English" on the right side of the screen if it fails to change automatically. Write in your ID number into the text box titled "Trainer ID." Select "HeartGold or SoulSilver" and your language of choice. Hit "Send."
Copy down the code words for the nine wallpapers: Trio, Spiky Pika, Heart, Soul, Kimono Girl, Pokeathlon, Big Brother and Revival.
Travel to Violet City, located west of Route 31. Enter the Pokemon Center and speak to Primo, located at the bottom of the staircase beside the front desk. Repeat the keywords that the website gave you to receive the wallpapers.