You need a Citi Premier, Prestige, or Chairman card.
That stinks, but it doesn't say it on the site in the first post?
Citi ThankYouŽ Rewards
Citi ThankYouŽ Rewards
Exchange Citi ThankYouŽ Points for HHonors Bonus Points
To exchange points from your Citi ThankYou Rewards account to your HHonors account, you must be a registered Citi ThankYou Rewards member.
Receive 1, 500 HHonors Bonus Points for Every 1, 000 Citi ThankYou Points. Transfers must be in increments of 1, 000 ThankYou Points with a minimum of 1, 000 ThankYou Points.
To make an exchange, visit thankyou.com or call ThankYou Rewards at 1-800-842-6596 (toll-free in the United States)