its real money, not DH credit.
be aware the discount is only for the first purchase, when you have to renew it will be at full price.
as for the question in the topic, use whatever promo code you want, you can see the discount it provides on the signup page before you pay.
Pay just [color=#CC0000]$22.40[/color] for 1 year Dreamhost hosting, use promo-code [color=#CC0000]MOJO97[/color]
Save [color=#CC0000]$97[/color] on all 1 and 2 year plans!! (Max saving on monthly plans too!!)