How do I redeem a gift card?

[adam.y.chao]

I have received a steam gift card which is from the “tremendous” app. However, it only shows me the “Name”(Steam USD), the "Pin"(a letter, followed by numbers: #############-####), and a "Claim Code"(a 15 character string of numbers and letters). How do I redeem this gift card??

[まりさ]

https://store.steampowered.com/account/redeemwalletcode