Why can't I change my CSS with jetpak?

I’m a newbie but understand CSS (or so I thought…) I’m using the bouquet theme (lily of the valley) and got jet pack to customize colors. I want to change the navigation bar color, and background colors of my pages where text is entered. I copy the current CSS into the jetpack editor, preview… but nothing happens. What am I doing wrong?
Thanks,
Chris
http://www.sagelandmedia.com