Homepage Header size and color

I'm trying to get familar with this them and I have a few questions. Is there a way to change the color of Homepage Header where you change logo? Is there a way to add an address on the top right side of header, you see the logo ( Catch Mustang  and that is it on the top, nothing else. On my About Us page, is there a way to change the width of the sidebar? It seems like its too wide. My site is gcautocare.com Thanks