Once a discount using the "Code" discount type has been set up, you can apply the newly created discount to any completed registration.
Note: Discounts that are not using the "Code" type may be applied in different ways.
Apply code to registration
To apply a discount code:
Go to People > Registrations
Locate the registration and select by either double-clicking the registration or clicking "Edit" icon to the right of the registration
Enter the discount code into the "Enter promotional code" box
Click "Update" to apply the discount to the basket
Once the desired discount is confirmed, click "Complete registration"