Add & save Metabox in wordpress post to enhance functionality

functions.php

add_action( 'add_meta_boxes', 'add_events_metaboxes' );

// Add the Events Meta Boxes
function add_events_metaboxes() {
    add_meta_box('wpt_events_location', 'Event Details', 'wpt_events_location', 'post', 'normal', 'high');
}

function wpt_events_location() {
    global $post;
    // Noncename needed to verify where the data originated
    echo '<input type="hidden" name="eventmeta_noncename" id="eventmeta_noncename" value="' .
    wp_create_nonce( plugin_basename(__FILE__) ) . '" />';
    // Get the location data if its already been entered
    $url = get_post_meta($post->ID, '_url', true);
    $fromdate = get_post_meta($post->ID, '_fromdate', true);
    $todate = get_post_meta($post->ID, '_todate', true);
    //$address = get_post_meta($post->ID, '_address', true);
    //$offer  = get_post_meta($post->ID, '_offer', true);
    //$status  = get_post_meta($post->ID, '_status', true);
    $showto  = get_post_meta($post->ID, '_showto', true);
    if($showto=='yes')
    {
    	$yes = 'selected';
    }
    else
    {
    	$yes = '';
    }

    if($showto=='no')
    {
    	$no = 'selected';
    }
    else
    {
    	$no = '';
    }
    // Echo out the field
    echo '<p>Enter Event Ticket Url</p>';
    echo '<input type="text" name="_url" value="' . $url  . '" class="widefat" />';
    echo '<p>Enter Event From Date (yyyy-mm-dd)</p>';
    echo '<input type="text" name="_fromdate" value="' . $fromdate  . '" class="widefat" />';
    echo '<p>Enter Event To Date (yyyy-mm-dd)</p>';
    echo '<input type="text" name="_todate" value="' . $todate  . '" class="widefat" />';
    echo '<p>Do you want to show to date of event in website</p>';
    echo '<select name="_showto" class="widefat">
            <option value="">Select Option</option>
    		<option value="yes" '.$yes.'>Yes</option>
    		<option value="no" '.$no.'>No</option>
    	 </select>';
    //echo '<p>Enter Event Address</p>';
    //echo '<input type="text" name="_address" value="' . $address  . '" class="widefat" />';
    //echo '<p>Add Event Offer</p>';
    //echo '<input type="text" name="_offer" value="' . $offer  . '" class="widefat" />';
    //echo '<p>Add Event Status E.g. (Live Recording,Sold Out,Ticket selling fast)</p>';
    //echo '<input type="text" name="_status" value="' . $status  . '" class="widefat" />';
    
}

// Save the Metabox Data

function wpt_save_events_meta($post_id, $post) {
    
    // verify this came from the our screen and with proper authorization,
    // because save_post can be triggered at other times
    if ( !wp_verify_nonce( $_POST['eventmeta_noncename'], plugin_basename(__FILE__) )) {
    return $post->ID;
    }

    // Is the user allowed to edit the post or page?
    if ( !current_user_can( 'edit_post', $post->ID ))
        return $post->ID;

    // OK, we're authenticated: we need to find and save the data
    // We'll put it into an array to make it easier to loop though.
    
    $events_meta['_url'] = $_POST['_url'];
    $events_meta['_fromdate'] = $_POST['_fromdate'];
    $events_meta['_todate'] = $_POST['_todate'];
    $events_meta['_showto'] = $_POST['_showto'];
    //$events_meta['_address'] = $_POST['_address'];
    //$events_meta['_offer'] = $_POST['_offer'];
    //$events_meta['_status'] = $_POST['_status'];
    
    // Add values of $events_meta as custom fields
    
    foreach ($events_meta as $key => $value) { // Cycle through the $events_meta array!
        if( $post->post_type == 'revision' ) return; // Don't store custom data twice
        $value = implode(',', (array)$value); // If $value is an array, make it a CSV (unlikely)
        if(get_post_meta($post->ID, $key, FALSE)) { // If the custom field already has a value
            update_post_meta($post->ID, $key, $value);
        } else { // If the custom field doesn't have a value
            add_post_meta($post->ID, $key, $value);
        }
        if(!$value) delete_post_meta($post->ID, $key); // Delete if blank
    }

}

add_action('save_post', 'wpt_save_events_meta', 1, 2); // save the custom fields

// Remove query string from static files
function remove_cssjs_ver( $src ) {
 if( strpos( $src, '?ver=' ) )
 $src = remove_query_arg( 'ver', $src );
 return $src;
}
add_filter( 'style_loader_src', 'remove_cssjs_ver', 10, 2 );
add_filter( 'script_loader_src', 'remove_cssjs_ver', 10, 2 );


# Show this metabox in template files example below :- 
$date = get_post_meta( get_the_ID(), '_fromdate', true );
$url = get_post_meta( get_the_ID(), '_url', true );
$fromdate = get_post_meta( get_the_ID(), '_fromdate', true );
$todate = get_post_meta( get_the_ID(), '_todate', true );
$showto = get_post_meta( get_the_ID(), '_showto', true );