In order to redeem points, make sure you are signed in to your account and you navigate to the regular site checkout (not accelerated checkouts like Paypal, Shop Pay, Google Pay, etc). You will see a "Choose Reward" dropdown in the checkout next to the gift card code box. Select the value of discount based on your points total and hit apply.
*Note, you cannot apply the rewards discount when checking out through accelerated checkouts (like Shop Pay & Paypal). You'll need to apply the discount in our regular site checkout before navigating to those payment options.