Select a customer for the invoice. Discount cards are associated with a particular customer.
Sell the item that you set up at the end of the Setting Up Discount Cards procedure
You will be prompted for the particular number for the discount cards you're selling to the customer.
Complete the sale, and that discount card will be issued, with an expiration date for one calender year from that date.
Note that for a discount card's promotions to apply, you must either hit "scan discount card" and enter the number, or hit apply discount card on the more information screen after selecting the customer