I added a flex nav bar component from the library but I can't figure out how to change the background color??

What framework are you using?
Foundation
Bootstrap
Materialize
Frameworkless

Mind you I suspect it's the same for all just make sure you do it for the lowest breakpoint first (or the highest if using frameworkless desktop down
1/ Go to the inspector pane
select the component

2 go to 'Styles' tab

select the 'Design' tab

there you should see a 'Background' tab with a 'Background colour indicated, select that box and a colour picker will appear,, choose your desired colour

I'm using bootstrap 4. When I change the color under styles/design the background box shows my new color with a small strip of the old color on the left of the box and the background cover remains the same. I am doing it under the smallest breakpoint.

the nav bar has 4 class names you can remove the class name bk-primary

once you have removed that class name you can choose your new colour.

or you can remove the class name bk-primary and without doing anything elese type in a new class-name (EG my-bk-primary) and then change the colour.

Thank you so much. I appreciate you!