The below steps to Configure ecommerce shop coupons:-
1) In Admin Role Menu  Settings --> Configuration --> Sales
Customer Features check "Use pricelists to adapt your price per customers" and Apply
2) Create/Edit  PriceList and Subtab Create PriceList Version and Price List Item using the below odoo document link 
https://doc.odoo.com/6.1/book/6/6_16_Sales/6_16_Sales_pricing/
  You can define/Edit a pricelist from the menu Sales --> Configuration --> Pricelists --> Pricelists
  For each list you should define:
 
  Promotional Code (is equal to Coupon Code)
  a Name for the list,
  a Type of list: Sale for customers or Purchase for suppliers,
  the Currency in which the prices are expressed.
 
   In sub tab create Price List Version and Price List Items
3) In the Page http://localhost:8069/shop/cart
   Menu --> Customize --> check "Reduction Code" after tht you can view "Coupon Code" options
   and Apply based on the Product Pricelist Rule amount will be calculate   
Hello!! I've noticed that this message was posted long time ago and I'm now in the same problem you were by that time. I would like to know if you found how to do it and if you could tell me how did you do. Thank you in advance. Maitane.