Old Console Users:

Follow this link.
Sign in to your Black Desert Console account.
Paste your code and hit Use. Your loot will be entitled to your account.
Go to My Page > Web Storage.
Redeem your rewards by selecting your desired character. Your loot will now be in-game.

New Console Users (Xbox & PlayStation):

Make an account on the Black Desert Console site.
On your console, launch Black Desert.
Create a character and choose class. Load into server.
Complete tutorial.
On your controller Dpad, hit Up to bring up the wheel menu. Select the profile icon (looks like a helmet).
From Profile, hit Y to open Link Accounts (or triangle on PlayStation).
Enter your Account Name (email address) and Password. Click Connect.
After linking your account, go here to redeem your code on the web.
Select your server and character, hit ´Use´.