Use this code: 

#wpforo #wpforo-wrap #wpforo-menu {
   background-color: #4a4646;
}
#wpforo #wpforo-wrap .wpforo-active {
   background-color: #465646 !important;
}

The CSS code should be added in the "Custom CSS code" textarea, located in the Dashboard > Forums > Settings > Style Tab.  

The red marked values should be changed as you like. 

Please don't forget to delete all caches and press Ctrl+F5 (twice) on the frontend before checking to reload the updated CSS file. 

You're asking your question on wrong forum. Please note, all questions related to the core wpForo plugin should be asked in the wpForo.com community. Here we support wpForo paid addons.   

we are looking to have a different color for the menu bar.

However we want the general font to be black.

How can we have another color for the menu bar. 

See attached screenshot, the black does not really look good

Thanks

Sven