Ok first you need to go into your system settings on your Ds system & change the connection setting.
You ad the DNS # that they provide & save settings.
Then you play your game & go to the GTS & try to deposit the pokemon you want to check.
It won't deposit & say the pokemon can't be traded & a #.
You then go to the site & a list of pokemon you tried to deposit should appear
If it doesn't you may have to use the search feature or access the site using your Ds
Note: When you are done depositing pokemon make sure you go back to your connection settings & change the DNS back to what ever it was before.
I hope this helps :)
Oh, I'm going off line for about an hour or 2 i need to tend to the horses & dogs. I'll be back on when I'm done :)