Where do you go after have members card on Pokemon diamond or pearl?

After you get the Members Card in Pokémon Diamond and Pearl, you can access the Pokémon Fan Club in Jubilife City. This club has several features:

* Pokémon Contests: This is where you can participate in Pokémon Contests to win ribbons and prizes.

* Trainer Fan Club: This area allows you to see your Trainer Card information.

* Auction House: This is where you can buy and sell Pokémon items.

The Members Card unlocks a lot of additional content and gameplay features in the game, so it's a significant milestone to reach!