add_action('wp_dashboard_setup', 'my_custom_dashboard_widgets');
function my_custom_dashboard_widgets() {
   global $wp_meta_boxes;
   wp_add_dashboard_widget('custom_help_widget', 'Theme Support', 'custom_dashboard_help');
}
function custom_dashboard_help() {
   echo '<p>Welcome to your custom dashboard! Need help? Contact the support here.</p>';
}