The menu is a quick fix luckily 🙂 Go to “Appreance -> Menus” and asign it to a theme location on the left on that page. That will snap the menu into place.
Regarding the customization; Go to the style.css file and search for “#top”. Change the background to something you’d like (#FFFFFF for white). Be sure to also change the color of the text inside it. Search for “#tagline p” and change the color to something contrasting.
Hope this helps 🙂