Demo for fieldmanager.org

fieldmanager-demo-1.php

<?php
// put this in functions.php or an include file
add_action( 'fm_post_post', function() {
    $fm = new Fieldmanager_Group( array(
        'name' => 'contact_information',
        'children' => array(
            'name' => new Fieldmanager_Textfield( __( 'Name', 'your-domain' ) ),
            'phone_number' => new Fieldmanager_Textfield( __( 'Phone Number', 'your-domain' ) ),
            'website' => new Fieldmanager_Link( __( 'Website', 'your-domain' ) ),
        ),
    ) );
    $fm->add_meta_box( __( 'Contact Information', 'your-domain' ), 'post' );
} );