You will need an ICONIC account in order to redeem your Gift Card. Log in to your account (if you don't have an account, you can create a new account) and redeem it by entering the PIN during checkout.
Any remaining value will be stored under the My Credit section for you to use on future purchases (valid for 12 months).
Don't want to use your Gift Card now? You can save your Gift Card to use for another day by storing the Gift Card credit in My Credit.