From Prekindle Help
You can add a promo code to a ticket to allow customers to see special price option once the code has been submitted on the event page.
To add a promo code, you must be logged into your Prekindle dashboard.
1) Click on the event to open the tools.
2) Click on the SALES tab and TICKETS tab for the event.
3) Click ADD PRICE on an existing ticket type to create a discount price and promo code.
4) Enter a name (ex: 1/2 price ticket, or Fan Club discount), and the price for the tickets that will only be available to customers with the promo code, then click SAVE.
5) Click PROMO CODE to enter the code that will unlock the special price (multiple codes may be entered, just separate them with a comma), and click SAVE
6) Click PUBLISH to make the promo code option available to your customers.
When customers submit a valid promo code, the discounted ticket will open up as a new purchase option.
Please contact firstname.lastname@example.org if you have any questions about entering or editing a promo code for your ticket sales.