Before placing an order, make sure you're logged in, and launch the Rewards Panel through the Clink Rewards icon found on your browser. Click on All Rewards.

If you don’t have enough points to redeem, you'll find a progress bar next to the reward names.

If you do have enough points, great! Simply click the Redeem button and you’ll be redirected to another page which shows your coupon code. Click "Apply code" to automatically apply it upon checkout. If you want to use it in the future, you can always find your code in the Rewards Panel under the Your Rewards section at the bottom.