You can see the list of available offers for your region on the Promocodes page.
Please follow these steps in order to fullfill the offer you liked:
Select the promocode by pressing 'Explore' button,
Read the offer description carefully and note the Expiration date and available regions as the codes are not applicable in any country,
Complete the purchase with your KCAL,
Promo code will appear under the Purchased tab once the purchase is completed
Please make sure that you have enough KCAL for purchasing a promo code,
It is possible to buy 1 uniques promo code per 1 user only,