To turn your Angel Points into a reward, log into your account, then click on the launcher to open the rewards panel.
Next, click on All rewards. If you don't have enough points to redeem, you'll see a progress bar on the right.
If you do have enough points, you can click the "Redeem" button.
After clicking redeem, you will be taken to the page that shows your coupon code and a button "Apply code" which will automatically apply the coupon code to your order at checkout.