Please follow to following process to change the background color of :-
Header site title
Goto admin menu >> appearance >> customizer >> typography >> Header site title
Header description
Goto admin menu >> appearance >> customizer >> typography >> Header tagline
Menu
Goto admin menu >> appearance >> customizer >> typography >> Menu
Section title of all section
Goto admin menu >> appearance >> customizer >> typography >> Section title
Post title of all section
Goto admin menu >> appearance >> customizer >> typography >> Post title
Date, no of comment and tag of blog post section
Goto admin menu >> appearance >> customizer >> typography >> Date, comment and tag
Paragraph of page detail / post detail and excerpt of banner / blog post
Goto admin menu >> appearance >> customizer >> typography >> Paragraph / Excerpt
Blockquote of sidebar , inside page / post detail
Goto admin menu >> appearance >> customizer >> typography >> Blockquote
Widget title
Goto admin menu >> appearance >> customizer >> typography >> Widget title
Widget list or widget detail
Goto admin menu >> appearance >> customizer >> typography >> Widget list
Category of banner, feature and blog post section
Goto admin menu >> appearance >> customizer >> typography >> Category
Read more and nave link that shows page number
Goto admin menu >> appearance >> customizer >> typography >> Read more and navLinks