To redeem an NCoins gift card for Blade & Soul, you can follow these steps:

Go to the website of NCSoft to log in or create a new NC Account 1.
Once you are logged in, click on Apply a code under My Account 1.
Enter the unique redemption code that you received by email under Serial Code, Game Card, or Game Time Card 1.
Click on Activate once you have entered the code correctly 1.
The code will now appear under the NCoin tab. Click on APPLY and youre done!