I want to trade over my good pokemon but I don't know how this poke bank thing works.

I can give you the simple version if you'd like <.<

You transfer all the pokemon you want to move into Gen 6 and the pokebank to Black/White or B2/W2. You have to beat the elites and go to the transfer lab to do this bit.

Then you purchase pokebank on your 3ds, $5 a year. Download the additional app of poketransporter.
Then you put your BW/B2/W2 cartridge in the 3ds and run the transporter. You move all pokemon from box one into a transfer box. Then it gets tedious because you have to keep swapping between cartridges to move pokemon from the transfer box in the pokebank to a storage box and then rinse/repeat.

It took me a few hours to move several boxes of pokemon this way <.<

But it's certainly worth it >.>