After opening the launcher, click on the button on the top right with the first letter of your username. That'll open up a menu, and midway down you'll find "redeem code." Simply enter your code into the page that pops up.
After opening the launcher, click on the button on the top right with the first letter of your username. That'll open up a menu, and midway down you'll find "redeem code." Simply enter your code into the page that pops up.