bonjour à tous (Hello Everyone)

i'm interested in selling candy and i've browsed the net and found similar companies..for instance:
www.candy.com/
www.candywarehouse.com
www.candydirect.com/

I'm wondering if these companies would buy there candy directly from the manufacture and then sell it on their website. If so would they need permission from the manufacture. (Mars Incorported for instance, the company that makes M&M's)

Does anyone know how this works?

All feedback would be sweet.

Thank You,
Tye