Adding a new div to an existing Responsive theme page

Hey guys!
A newbie one here I’m afraid, hope someone can help.
I’ve basically been ripping apart and customizing the Responsive theme. On the home page with Featured content on, I have placed a slider in place of content and deleted the 3 home widgets at bottom (see https://www.firstclassdogtraining.org).
All I want now is to add a couple if divs, or a 2 column div underneath the slider :/
Can someone point me in the right direction please?
Thanks in advance.