I don't shop Old Navy but thought some of you could use this. From what I understand, you need to go to www.oldnavy.com when the website updates each week (as coupons are limited) and mouse-over parts of the site until you find the coupon you want.
The Old Navy coupon website has been updating at between 6-9PM western time on Thursday evening for the last 3 weeks.
Here is a video (not by me) that shows what to do:
Old Navy Coupon Instructions