In this video tutorial you will learn how to set up coupon codes:
If you want a coupon code to only be applied to the front end of a funnel, do not select "Funnel" in the drop down, but rather select the individual product in the "product" drop down.
If a product isn’t active it will not be listed in the drop down menu of products.
Coupon codes can only contain numbers and letters, and must be one word.
or Set up a coupon here.