how to display contents in dashboard window in wordpress

this is a simple example to display user in the admin site

<?php
/*
Plugin name:dashboard
*/
function dashboard_widgets() {

wp_add_dashboard_widget(
                 'dashboard_widget',       
                 ' Dashboard Widget',       
                 'dashboard_widget_function'
        );
}
add_action( 'wp_dashboard_setup', 'dashboard_widgets' );
function dashboard_widget_function() {
$admin = get_admin_url()."user-edit.php?user_id=";
$users = get_users();
foreach($users as $key=>$item)
{
?>
<a target="_blank" href="<?php echo $admin.$item->data->ID; ?>"><?php echo $item->data->display_name;?></a><br/>
<?php
}
}