You're talking about a user image. It's a unique 200x40 image that has to reflect the color of the usergroup you're in, in which case that would be white for you. You can request someone make one for you in graphics marketplace, or make one yourself. After you have the image, go to your user center, click on the drop down and select user image. There should be a box where you need to place the image url in. After saving your request, it will take a week for Matthew to update it to your profile.
If you need inspiration on how you want your user image to look, here is a user image directory.