Have you linked your DS up to wifi yet? You will need to take care of that first of all. It's easier than I thought it would be but you're going to need your WEP key, I had to call Linksys to get mine. There's tons of online instructions for linking up..
When you trade a Pokemon, if someone is "giving" you one you just need to set your party with a "filler" pokemon as they're called, one you don't care about losing. (I just catch random Bidoof's for this purpose, as do many others lol.) You can't do a "trade" in the game without sending something over as well.
You find someone on the forums who has a poke you want, then you go to a Poke Center in the game, go downstairs and connect to the wifi. Make sure you have already added the person's friend code into the pal pad thingy.
I was asking all the same questions you're asking a few days ago! lol Now I've been trading like crazy!
