First, on the BigCommerce side of things:

  1. Sign in to your dashboard and create your Coupon Code.  This action can be found under the Marketing menu item. 
  2. Make sure you have the "Limit number of uses per customer" set to 1 if you want it to be useable only one time.  
  3. Copy the Coupon Code.

Next, on the Apptive side:

  1. Sign in to your Apptive account.
  2. Click the Deals module in the left side menu (This action can also be performed with the Messages module)
  3. Scroll down and click "Add Another Deal"
  4. Add an image for your Deal if you would like
  5. Add a Deal title
  6. Add your Deal description.  This is the part where you'll want to mention your coupon code - something like: Use this coupon code at checkout to get 15% off your first order!  Coupon Code: FIRSTORDER
  7. You can leave Start Date and End Date empty if you want this deal to not have any time limit associated with it.
  8. Leave Price blank.
  9. Scroll down and click the check box that says "To send out a push notification for this update, check this box:" and schedule when you would like a push notification to go out about this deal.