The promotional code box is located just above the Check Availabilty Calendar.

Enter your Promotional Code in the Box and then hit the "Go" Button.

Once you've properly entered your Promotion Code, your discount will be reflected in prices shown for each tour.

If you don't see these discounted prices, then you have not entered your Promotion Code correctly.

So make sure you see the discount before you move on past the screen where you're asked to enter the Quantity of Adults, Children, and Seniors or else you will be charged the regular price for your tour, not your discounted price!