How to change color in only one menu page tab

Hi

Probably this has been asked before but I couldn’t find anything.

I have a menu bar with 6 page-tabs on the top of my website. I suppose it’s possible to change the background color of these menu page tabs, or specifically only one of these tabs? I want to have one page-tab in the menu bar stick out from the rest. Currently I use the light grey color template. Needless to say, I am a kind of a dummy when it comes to CSS and stuff. Please try to have this in mind when explaining 🙂

Thanks in advance!
David