Its on the home tab of the dashboard. Just wait for it to scroll through the offers in the middle of the page and you should eventually see it.
(sorry if I'm not very good at describing it.. I'm usually a guy and recently moved over to the xD)
"5 games free when you purchase a 6 month xbox live gold membership"
the games listed are:
"Games will be sent as codes to your email for download"
some important points from the fine print:
"Offer valid only though this in-dash signup with credit card. While supplies last."
"not valid on prior Xbox Live membership purchases"
Full payment for the 6 month subscription is required to receive the free games. Redemption codes will be sent to the email tied to your Xbox live account within 4-6 weeks and must be used by June 30, 2012. Limit 1 per acc."
Edited by ken9, 25 March 2012 - 06:26 PM.
added points from the fine print