Customize

This is where you can preview your Theme and customize your site. You can change the Layout for all the pages Site Title, Tagline and add a image to the header text.

Site Title & Tagline

This is the title and subtitle or tagline that will be displayed in the Header of the site as shown in red in the image below. You can add text to the header or have “Display Header Text” unchecked.

Customize-Site_Title_and_Tagline

Colors

This will can the will change the color of the Title in the Header as shown in red in the image below.

Customize-Color

To can the Tagline/Subtitle/Description, you will have to use the Custom CSS.  To do this use this code:
#site-description {
color:  "Name or Hex Code of Color";
}

Color Example:
#site-description {
color:  Black;
}

Hex Code Example:
#site-description {
color:  #000000;
}

Custom CSS

This is where you will place all the CSS code (look and formatting of the site) to make changes to your site that cannot be made anywhere else in WordPress.

Customize-Custom-CSS

Select this site to learn more about using CSS: http://www.w3schools.com/css/.

Layout

Note: This may not be present on all WordPress themes or menu. If this is not shown you can change the layout of a page by changing the Template in Page Attribute in a Page.

This is where you will be able to select how the website is displayed. You can have the content shown on the left of site as marked in red in the image below and sidebar on the right as marked in black or have them flipped.

Customize-Layout

If you only want the content to be placed, you can select the “One-column, no sidebar”. This will hide the sidebar.

Note: Changing the Layout here will effect all the pages. Go to Layout Settings in Pages to change the layout of that page.

Navigation

This allows you to select a menu to be displayed.

Note: You to create a menu in order for it to be used here.

Customize-Navigation

Static Front Page

This allows you to change what is displayed on your home page.  A static page is your Home page you created or a post page.

Customize-Static_Front_Page

Note:  The layout of a single page can be changed by going into a Page changing the layout.

For more information about WordPress Customize click here https://codex.wordpress.org/Appearance_Customize_Screen.