You can follow the below guide on how to add your Promo code to your deposit:
Click on the Wallet tab at the bottom of your screen
(you will find all available deposit methods according to your registered country)
Choose your preferred Deposit Method (Let's use Credit Card for this example)
3. Fill out the required card details, the currency and the amount.
Then click on I have the Promo code!
4. Enter the Promo Code and click on Save.
5. You will now see the Promo Code attached to your Deposit.
6. Click on Deposit to complete your Deposit and you shall receive a notification that your Transaction has been approved with your Promo Code.