You should have received a (crazy long) serial number with your order. Do you have that? (looks like:b0328742-xxxx-xxxx-xxxx- xxxxxxxxxxxx) I'm able to email it to you if not.
You'll simply want to put this into the coupon code section on the shopping cart page, hit "update cart", and it should be applied to your order.
The cards can be used towards the Ransomed Heart Wild at Heart and Captivating retreats, but not towards other events such as a simulcast.