I have activated the plugin and ALL in one SEO plugin option is also seen in WP Dashboard

I have also found that desc tag is not visible in header.php file
Do we have to add deswc tag here?

<!DOCTYPE html>
<!--[if IE 7]>
<html class="ie ie7" <?php language_attributes(); ?>>
<![endif]-->
<!--[if IE 8]>
<html class="ie ie8" <?php language_attributes(); ?>>
<![endif]-->
<!--[if !(IE 7) | !(IE 8) ]><!-->
<html <?php language_attributes(); ?>>
<!--<![endif]-->
<head>
<meta charset="<?php bloginfo( 'charset' ); ?>">
<meta name="viewport" content="width=device-width">
<title><?php wp_title( '|', true, 'right' ); ?></title>
<meta name="google-site-verification" content="pK5qdtBXGbYD9T7Qi2S5_wNvI7UWZADsQz8jrtU8n 8Q" />


<link rel="profile" href="http://gmpg.org/xfn/11">
<link rel="pingback" href="<?php bloginfo( 'pingback_url' ); ?>">
<!--[if lt IE 9]>
<script src="<?php echo get_template_directory_uri(); ?>/js/html5.js"></script>
<![endif]-->
<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/css/app.css" title="" type="text/css" />
<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/assets/vendor/nivo-slider/nivo-slider.css" type="text/css" />
<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/assets/vendor/nivo-slider/themes/default/default.css" type="text/css" />
<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/assets/css/lightbox.css">
<script src="<?php echo get_template_directory_uri(); ?>/js/vendor/jquery.js"></script>
<script type="text/javascript">
jQuery(document).ready(function($) {
/* TABS FUNCT FOR RECIPES */
$j = jQuery.noConflict();
$('.smoothies, .cocktails, .bowls, .hm').show();
$('.recipe-tab').click(function() {
var type = $(this).attr('id');
if ( type === "all" ) {
$('.smoothies, .cocktails, .bowls, .hm').fadeIn();
} else {
$('.smoothies, .cocktails, .bowls, .hm').hide();
$('.' + type).fadeIn();
}
});
});
/* END TABS FUNCT FOR RECIPES */
</script>

<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');

ga('create', 'UA-61582035-1', 'auto');
ga('send', 'pageview');

</script>
</head>
<body <?php body_class(); ?>
<?php global $woocommerce; ?>
<header id="main-header">
<div id="head-row1" class="row">
<div id="logo" class="small-3 large-3 column">
<a href="<?php echo site_url(); ?>" >
<img class="logo-large" src="<?php echo get_template_directory_uri(); ?>/assets/images/home/nativo_logo.png" alt="" />
<img class="logo-mobile" style="display:none" src="<?php echo get_template_directory_uri(); ?>/assets/images/home/nativo_logo_mobile.png" alt="" />
</a>
</div><!--logo end-->
<!--addons-->
<div id="wholenav">
<nav id="secondary-nav" class="small-3 large-3 small-offset-2 column">
<?php wp_nav_menu( array( 'theme_location' => 'primary' ) ); ?>
<a id="head-cart-contents" class="cart-contents" href="<?php echo $woocommerce->cart->get_cart_url(); ?>" title="<?php _e('View your shopping cart', 'woothemes'); ?>"><?php echo sprintf(_n('%d', '%d', $woocommerce->cart->cart_contents_count, 'woothemes'), $woocommerce->cart->cart_contents_count);?> <?php /* echo $woocommerce->cart->get_cart_total(); */ ?></a>
</nav>
<nav id="main-nav" class="small-5 column">
<?php wp_nav_menu( array( 'theme_location' => 'secondary' ) ); ?>
</nav>
</div><!--wholenav-->

<div class="row mobnav">
<nav class="top-bar" data-topbar="" data-options="is_hover: false">
<ul class="title-area">
<!-- Title Area -->
<li class="toggle-topbar menu-icon"><a href=""></a></li>
</ul>

<section class="top-bar-section" style="left: 0%;">
<!-- <?php wp_nav_menu( array( 'theme_location' => 'secondary', 'menu_class' => 'left' ) ); ?> -->
<?php wp_nav_menu( array( 'menu' => 'mobile-menu', 'menu_class' => 'left' ) ); ?>
</section>
</nav>
</div><!--mobnav end-->

</div><!--main row end-->
</header>

Can you please let me know any description tag which I can add in my header file?

Thanks a ton, it solves my issue. Now plugin is showing everything. I have added this in header file
<?php wp_head(); ?>