WordPress has a very simple and convenient automatic updating process. But for making this process work, you need a working ftp server on your server and the filesystem permission for that user to access your htdocs-folder on your system. Furthermore, some lines in wp-copnfig.php are needed:
define('FTP_HOST', 'ftp://localhost');
define('FTP_USER', 'my_username');
define('FTP_PASS', 'my_password');
define('FTP_BASE', '/path/to/my_web_root/');
define('FTP_CONTENT_DIR', '/path/to/my_web_root/wordpress/wp-content/');
define('FTP_PLUGIN_DIR', '/path/to/my_web_root/wordpress/wp-content/plugins/');
With all these settings, the update is just one click away!