"Once you have the Pal Pad, you will need to go on Nintendo Wi-Fi Connection for the first time to revive your Friend Code.
After you have gone on Wi-Fi Connection once, go to your Key Items Bag and select the Pal Pad. The first option will show your Friend List. The second option will let you register Friend Codes. The third option will show you your Friend Code."
found that n yahoo answers, it must've been what i did, haah.