Create pop up banner

Hi all,

I saw the site AdamEvedotcom have a very attractive popup banner, so I want to create a similar popup banner for my site (selling men's health products). I want to create a popup banner that show visitors the coupon codes when they check out. I have been search for how to creat pop up banner on the Net but still haven't found the correct answer.
Any one know how to create this popup banner can help me?

Thank you in advance!

You can probably use a autoresponder to create a popup like that. I have created a popup for my website.