You will be taken to promotion code page.You dont have to use yahoo promo code.

Offer open only to new Yahoo! Domains customers purchasing a new web domain through Yahoo! Small Business. Offer expires 12/31/2010. Discount applies only to the first year of service. Limit one offer per customer on a single account for customer’s own purchase only. Offer may not be combined with other offers or discounts, transferred, exchanged, or redeemed for cash. Other terms and conditions apply; see the Yahoo! Small Business Terms of Service when you sign up.