How to add theme customization section?

/*custom theme customize options
call get_theme_mod function for fetch the value.
For Example: for receiving a value of heading
get_theme_mod("custom_theme_customize_setting");
*/

function custom_theme_customize_options($wp_customize){

$wp_customize->add_section("custom_theme_customize_area", array(

"title"=> "Custom Theme Settings"

));

$wp_customize->add_setting("custom_theme_customize_setting", array(

"default"=> "Tested By Prashant Kansal"
));

$wp_customize->add_control("custom_theme_customize_control", array(

"label"=> "Enter Heading",
"section"=> "custom_theme_customize_area",
"settings"=> "custom_theme_customize_setting"

));

}

add_action('customize_register', 'custom_theme_customize_options');