Header Banner - This is the banner that appears at the top of your campaign and has an optional click through. If you upload a banner here you will want it to be 760 pixels wide, but also look good at 520 pixels wide. In tab view the banner will cut off at 520, and in canvas view the remaining 240 pixels will display, so be sure it looks good in both forms. In step 2 of the header  banner you can put in a link. This is the URL users will be taken to if they click on your header banner .However, if you are planning on using CSS and design resources to brand your promotion, you may ignore this tab. To read more about CSS please see the Using Cascading Style Sheets (CSS) tutorial.