The Radar tells you everything about transferring, but here's the rundown: you play the DR for a bit and get some cool stuff (I think it has ten slots and items stack), when you want the stuff you tell it to transfer and then in your games main menu you go to Unova Link and then it's the third option. After you have done that it transfers your items into your bag and your Pokemon to the box.
You can play with the Radar and get Pokemon before you start playing B/W2 so like I have now, before the second town, a team of Snivy, Drifloon, Munna, and Riolu. The DR ones came to me at level 5.