This is already asked here,
Also im not sure but i think maybe this is the second time you ask this, however, i could give you an explenation on how to migrate.
First, you need a DS Lite or the Nintendo DS, (Dsi,DsiXL and 3ds will not work)
Then insert the game you want to migrate from in the GBA Slot (GBA Stands for GameBoyAdvance)
Then start your Compatible DS and go to the meny where it says Trainer Badges Play Time, and scroll down to where is says "migrate from "For example Sapphire" and prees it, from there, the DS will give you instructions and when you have migrated pokemon, they will be at the pal park wich is South East from Sandgem down (you need to surf)
btw you need to migrate 6 pokemon at the time.
If you have any problems, leave a comment, not another question.