I would to take nav menu reference (I have id and class) from plugin to theme header.php...How can I do this?
I used something like this
<?php wp_nav_menu('id'); ?> but of course with failure cause I didn't specific from where I pick this menu...How can I do?
wp_nav_menu() doesn't accept a single value for a parameter, it takes an array. Proper format (if you are looking to simply call the menu by ID) would look like this:
wp_nav_menu( array( 'menu' => $menu_id ) );
I'd recommend checking out the full reference in the codex for more information on the available parameters for displaying a menu.