@Anonymous User Yep that's OK, so you should receive a code in a separate email to get your Box Office fight free.
Not bought it myself but what I imagine you need to do if you haven't already got a Box Office account is go to https://skyboxoffice.neulion.com and click watch and then fill in your details on the first page and that should register you for an account. It does say you don't need to enter credit card details to use the voucher so I'd guess on the payment page there will be a box to enter the code you received. If not you can always go back to the link on the email the code came in and enter your username and password there.
Once the fight is purchased with the voucher on the website you should be able to log into the app on your box.
