Header Color

Hi there, I have the Highend theme, and I was wondering how to change the Header background colour to Black. I see the colour settings in customizer and it seems as though I can’t find an option to customize the background colour for the header and entire menu background at the top.

I have a white PNG logo uploaded but I need to make the background black so I can see it.

Please let me know if you know how to do this. Your help would be very much appreciated. Thanks!