How to use this redeem code on an Xbox one

So when I got Halo Reach and it came with a redeem code for a Recon helmet. It gives instructions on how to download it with the code on a 360 but I’m not sure how to do it on the One. Anyone know how to do it?

Here you go.

Please note that if you initially download 360 DLC on the One, you won’t have access to it on the 360. I don’t know why that happens, it just does.