Change menu item color or background color or "button" it.

Hi Tom,

First I thank you for this great theme. It enables me, one who knows nothing about coding, to make really beautiful websites.

Right now I have a need to make one of the menu items a more easy to notice color than the rest menu items. Or a button for this item(preferred a green button with white text), or a different back ground color for it.

Please check the link here: http://interpreterdatabase.com/, I want to change the "interpreter community" menu item at the right side of nav menu.

Could you please teach me to do this please?

Thanks in advance.
Leon