How to change menu bar color guys?
(https://www.simplemachines.org/community/proxy.php?request=http%3A%2F%2Fi65.tinypic.com%2F2je90rm.jpg&hash=c58a22b968bef420fe61246e3e5a1316bf2dbdbf)
What theme is that?
https://www.simplemachines.org/community/index.php?topic=547193.0
Assuming they didn't use an image... Go to your browser's dev tools (you can right click and inspect for that), find where are the colors, edit them to your liking and then change the color in the css file for your theme.
If they did use an image... Just find it and edit it.