Click Manage Restaurant followed by Coupons

Then "Add Coupon"

Once the coupon form is loaded.

1) Enter the Coupon Code.  This could be anything, but make it something short and simple. Like "10OFF" or "OnlineOrdering" etc..

2) Enter the description for the coupon.

3) Enter the Amount  - This could be any number

4) Pick "$" or "%" . This means the amount will be used as a dollar amount or a specific percentage.  For example, $10, or 10% off of any order.

5) Expiration - Pick an expiration for the coupon. This could be from 1 day to a year+

6) Check Public to make the coupon visible on the site for use by all OR leave it unchecked so it becomes a private coupon & only those that have the coupon code can use it.

7)  Rules.  Enabling Rules & setting a "Rule Amount" means the coupon will be used only when the order total amount is a certain this amount or higher. Example, if you put 25, this means the coupon code gives 10% or $10 off any order $25 or more.  

8) Save/Submit the coupon so it's saved. You can create more than 1 coupon code.