You can add any loyalty points you have earned from previous orders when checking out. There are 2 opportunities to do this:
1. Shopping Basket - below the order total click on the '+' sign on the menu titled 'Would you like to use a loyalty code, or loyalty points?'. Enter amount of points you wish to use and click 'Update Basket' button.
2. Payment Page - in the top right of the payment page you can see what points you have. Enter how many you want to use in the box and click on 'Apply' button.