How do I redeem a Riot gift card?

When you purchase a Riot gift card, you redeem the received code in the Valorant game. 

You log in to the Valorant client and click on the Valorant icon. It will ask you to select the purchase method. From there, you scroll to the right, where you will see a section called "Prepaid cards and codes".

That is where you enter the code that you received from Stryda.