I think I understand your question.
When somebody signed up a hosting plan using your promo code, you will receive 97 dollar rewards (depends on your promo code). You can check your account balance via DH panel --> Home --> Rewards
You can see the rewards but can't cash them out if your customer is less than 97 days old.
You can cash them out if your customer is more than 97 days old or you are a platinum member.
And finally here is your answer. You can use these rewards to pay for your hosting plan as well.
$50 off and 3 free domains with code: [color=#CC0000]DH3[/color] [url=http://dreamhost.com/r.cgi?296804/signup|DH3]Sign Up NOW[/url] or More Codes Here