OK, so I've recently become inseperable to my YouTube account and I seem to be adding a video every 2 minutes, but I was wondering how I get those little banners that some people have above their picture.

I obviously have a profile picture, but I've noticed other people have these long images, often with a little arrow pointing to the subscribe button. I've looked all over my channel customization options but I can't work out how on Earth I add one.

Help anyone?