It is very easy to show unread message & announcement count in menu. There are numerous way to do this. Please follow any method bellow as you feel comfortable.

Adding PHP code:

This is recommended way but you need a little knowledge in PHP code editing.

Add following code in your theme’s (child theme’s if any) functions.php

add_filter( 'wp_nav_menu_items', 'fep_cus_add_menu_link', 10, 2 );

function fep_cus_add_menu_link( $items, $args ) {
    if ( $args->theme_location == 'primary' ) {
        $items .= '<li><a href="'. fep_query_url( 'messagebox' ) .'">' . sprintf(__('Message Box%s', 'front-end-pm'), fep_get_new_message_button() ) . '</a></li>';
    }
    return $items;
}

Change theme_location primary text as you require. Or if you already added your menu just use require parts from here. main idea is to use fep_get_new_message_button() to show unread message count. You can see this function in code of this plugin to get accepted arguments.

Adding Shortcode:

If you do not want to use PHP code change you can easily achieve same functionality using shortcode.

Go to your website back-end and add menu item. Make Navigation Label or Link Text of your menu as Messages (Change “Messages” with whatever you like but keep the shortcode).

Then add add_filter('wp_nav_menu_items', 'do_shortcode'); in your theme’s (Child theme’s if any) functions.php.

Please note: do_shortcode is a resource intensive function.

To know more about this shortcode and its accepted arguments see https://www.shamimsplugins.com/docs/front-end-pm/shortcode/fep_shortcode_new_message_count/

Adding class:

If you do not want to parse shortcode in your menu then you can follow this method.

Go to your website back-end and add menu item. Make Navigation Label or Link Text of your menu as Messages<span class="fep_unread_message_count"></span> (Change “Messages” with whatever you like but keep span).

Then add following code in your theme’s (Child theme’s if you are using) functions.php.

add_filter('fep_filter_notification_call_on_ready', '__return_true');
add_action( 'wp_enqueue_scripts', function(){
    wp_enqueue_script( 'fep-notification-script' );
});

Remember this will make an ajax request every time after page load to get unread message count.