Need help w/new sound system

I just had a new sound system installed in my '04 Passat and am having troubble finding a part that will allow me to control songs and volume through the steering wheel. Here is the deck I bought: http://www.bestbuy.com/site/olspage.jsp?skuId=7652382&type=product&productCategoryId=cat03066&id=1134701297638

My question is, is there a part I can buy that will allow me to control sound and songs through the steering wheel?

Any advice would be great

Thanks,

CJ