Discount code feature which is available in your account. This feature will allow you to set a certain % or $ value of discount on per album basis. Which means you can set as an example either $10 or 10% off all orders on a particular album. Please note that this is set at the album basis so it will be applied to all orders for a particular album after shipping and taxes.
To use this feature you can login to your control panel. Click on "Set prices and options". Now click on option 2 "prices" and then "Discount Coupons". From this link you can easily create discount coupons codes for you online albums.
The "enter coupon" link will only appear on those albums which have any coupon available. The link is shown on the shopping cart page, please see the screenshot below: