How do i trade with people on pokemon diamond through having their ID numbers?

Ive got the national dex and everything and i want to get a charizard but people keep giving me a ID number. I put it into my pal pad but what next. does it involve the battle tower????How do i trade with people on pokemon diamond through having their ID numbers?
Once you and the person you're trading with have put each other's friend codes/ID Numbers in your respective Pal Pads, go to a Pokemon Centre and go downstairs to the Wifi Area. Talk to the ladies behind the counter and they'll guide you through the process to get connected to the Nintendo WFC to trade, provided that you have already set up a Nintendo Wifi Connection access point.





Once online it'll show you if anyone else on your friend roster is online (i.e. Someone else on your Pal Pad whom you've exchanged numbers with). Then just select that you either want to open a trade or battle invitation (in this case trade) and wait for them to accept your trade invitation (or if they start the invitation - it'll have a trade or battle symbol next to their name - you just need to select their name on the list and press A, etc). Then just go through the normal trading process by each selecting your pokemon to trade and press the button to initiate trading.How do i trade with people on pokemon diamond through having their ID numbers?
Dont' you go to the Pokemon centre and go upstairs (or down stairs, ican't remember) then talk to one of the people or go on one of the computers?





Soz i can't really remember i played it like a month ago.
ya do what those peepz said