Hi Joan,

When you're setting up an event, you'll need to choose "Use Custom Registration" under the Registration Options section, where you'll set up the regular-price registration type - then you'll see a below it which says "Add a discount code."  Click that to add a discount code.  You'll be able to enter the text of the code (what your participants will need to type in to get the discount), the date it expires, if applicable, and the amount of the discount.  The amount you enter will be subtracted from the registration fee.

Have a great day!

Camille