To add a new promotion:

1. From Manage, go to Store > Promotions
2. From the Promotions page, click Add
3. Select Discount Type
4. Type in Discount Name, Coupon Code,Discount Percentage and Maximum Discount Amount
5. Click No for Requires Coupon Code if you don't want a coupon code for the discount.
6. Click No for Use Percentage​​​​​​​ if you don't want the discount in percentage and type in Discount Amount
7. Type in Active From and Active To
8. From the Discount Limits​​​​​​​ section, click Yes for Combine discounts with other manufacturer, category, and product discounts​​​​​​​ if you want to combine the discount
9. Select Discount Limitation and type in Maximum Discounted Quantity​​​​​​​ 
10. Click Save