To be able to use and redeem these skins you are first required to already have a character in the game. For that visit: https://www.florensia-online.com/en create your account, download the game and create your first character.
Once you have created your character head back to https://www.florensia-online.com/en , log into your account and select "Redeem your Code" in the [Account] tab.
Finally, enter your code, select the items and the character you want them to be sent to and you're done.
You will receive an ingame email containing your item.
The AP will directly be added to your accounts wallet.
Please note that the AP provision might take longer than the receiving of the item.