How do i download the hoth mission on star wars the force unleashed?

I wanna know because i have star wars the force unleashed for the xbox 360 and i have xbox live but i don't know where to download the hoth mission.So how do i download the hoth mission?Plus is it free or do i have to pay for it?|||Go to your Xbox Live Dashboard and make sure the game is in. Once the game icon loads and says Play Game press Y and you'll see some options come up, choose downloads and you'll see it. It costs about 10 bucks not really worth the price because it only takes about 45 minutes to beat, but it is really fun.