i want insert a dropdown menu with list of menus, that i've created in nav-menu.php, to post-admin...

For example, when i'm creating a post, i want insert a menu "Paul" in a post (only a post that i want) selecting a menu at right sidebar of Admin-Post.

I've copied the rows:

add_action( 'init', 'register_my_menus' );
function register_my_menus() {
    register_nav_menus(
        array(
            'primary-menu' => __( 'Primary Menu' ),
            'personal-menu' => __( 'Personal Menu' )
        )
    );
} 

in a post.fields.php that i've created, don't work. :(

Can you help me in that fantastic problem? :(

ps: Sorry for my bad english

Francesco