Create and style menu

In your theme’s functions.php, write the following code:

<?php
/* ENABLING CUSTOM MENUS
-------------------------------------------------- */
//add_theme_support( 'menus' );

    register_nav_menus(
        array(
        'primary'=>__('Primary Menu'),
        'secondary'=>__('Secondary Menu'),
        )
    );
?>

It’ll register two custom menu area for your theme.
Then you need to achieve it with in header.php:

<?php wp_nav_menu ( array ( 'theme_location'=>'primary', 'fallback_cb'=>'') ); ?>

This code will place only the Primary Menu area in your theme.
Now you need to code the CSS, and These whole bunch of code is really amazing! I found it from a tutorial site.
Try it and then modify it as per your need, and then find the author of the code (not me) and thanks him. 🙂