Theme Horse

Hi erin,
We have designed our theme this way. It needs code customisation. So you need to hire a developer and if you are good at coding then then file is inside theme folder -> inc -> structure -> header-extension.php but We recommended not to change the code because if you change the code then while updating to our new version all your customisation code will be lost. So better make child theme and first unhook the functions and the edit the code.

http://codex.wordpress.org/Child_Themes

Thank you!