1) Log into your event > manage event > Discounts
2) Add new code > You can then choose the status. Set it to public if you want to push it onto DesignMyNight pages. You can choose to hide it from your ticket page in case you are linking to this page from your own website and you do not wish your own users to use the code.
The code will then go live on your DesignMyNight ticket page and across other channels to advertise the discount and drive sales.