rj@southgate on "[Theme: Responsive] Call to action box"

Hello,
I am completely lost!
I chose the responsive theme as I wanted the large call to action box on the home page. However, I really don't know where to start with adding an image, call to action link and text to this box. Where do I go on the dashboard to edit this area of the site? All I've managed to do so far is change the background colour!
Any help would be so appreciated. Thank you.