1- Go To Dashboard. 2- On The Home Tab, Right Beside The Quickplay You Will See A Tab That Moves. 3- In That Tab You Will See Summer Of Arcade And Click That. 4- Very Bottom Right Is Minecraft, Click That. 5- Click Get Skin Pack. Hope This Mini Guide Helps!
Try reloading the dashboard a few times. My ad in that section changes. i had to turn off/on my xbox a few times before I got the right one.