Pokemon Mystery Gifts and Wonder Cards?

I know I'd probably get more help at a gaming or Pokemon forum, but can someone here please explain how Wonder Cards and Mystery Gifts work in Pokemon Platinum, HeartGold, and Black?

Tried googling it but I got very confused. From what I understand, to get Wonder Cards, you have to get Mystery Gifts, but to get Mystery Gifts, you have to have Wonder Cards first. So I need a detailed explanation for Wonder Cards and Mystery Gifts.

Thanks!

Mystery gifts are promotional pokemon/items that Nintendo releases through wifi distributions. To see if ther is one going on, go to the menu screen of the game, and select the option "Mystery Gift." Then select the option "recieve gift by Nintendo WFC." Your ds system must be conected to wifi to do this. If there is a gift, it will pop up on the screen. Select "Recieve Gift." You will then be told to pick up your gift from the man at the PokeCenter. You will also recieve a Wonder Card, which is bassicaly a record of you having received the gift. Boot up your game, and go to the man in green at the PokeCenter with an empty slot in your party. He will give you your gift. Well, hope I helped :)