If you have found a discount that fits your travel plans, make sure you use it correctly. First, select your check-in and check-out dates.
Then, select the number of rooms as well as guests per room. In the column next to where you enter this information, you will see special rates.
From here you can select Corporate/Promotional code and enter your Marriott discount code in the blank text box below. Click 'Continue' and your discount will appear in the final price for the room.