That dark strip at the top and the gray area below it are a background image. If you want to change that in the Dark Knight skin, you'll have to replace the image.
The slide show uses jQuery Cycle and it is built into a special container. If you want to change the behavior of the slide show, you will need to edit the file Portals\_default\Containers\DarkKnight\Banner.ascx.
As an aside, this is not the way that I would have done things. You can build the required HTML structure containing the images in the contents of an HTML module. Then, you place the scripts to call jQuery.cycle in either the header of footer of the module.
If you look at the page source for http://investedinc.org
and look for Module 355, you will see the sort of structure that is needed. (That actually uses the Engage Rotator module which builds the HTML structure and calls jQuery.cycle to do the work.)
On that same page, the "Featured Board Member" module uses a Razor script to build the structure to be rotated, and uses jQuery.cycle in the module's footer section to call the rotator. It rotates a bit more than just a picture.