Question:How can you change your site appearance in WordPress? 

In WordPress we can change site's appearance by using customizer, widgets, the menu manager, and uploading custom hearer and background images.
go to Appearance > Themes and click Customize button under active theme.

Question:What is theme customizer? 

The theme customizer is a relatively new feature in WordPress. Its allow not only preview theme, it allow also make change the theme setting and see the effects in real time.

Question:What are the sections available in WordPress customizer? 

The most common available sections in WordPress customizer are:
               Site Title and tagline
               Colors
               Header Image
               Background Image
               Widgets
               Static front page

Question:What is widgets in WordPress? 

Widgets :  * The widgets offer a powerful way to change up WordPress site without touching a single line of code.* WordPress contain a dozen built in widgets* We can more widgets from the plugin repository* Some themes of WordPress use their won widgets

Question:How can you add CSS without editing the stylesheet in WordPress? 

There are two ways to handle CSS. If just need to make some small CSS changes we can do so using Jetpack plugin includes a custom CSS module. 
For large changes, we’ll need to create a child theme.

Question:How can you add CSS with a child theme? 

To create a child theme, simply create a new subdirectory in wp-content/themes. Add a file called style.css. 
This file must contain two things: a comment block defining the theme, and an import of the parent theme’s 
stylesheet.