If you have received an update notification and you want to update the plugin to the latest version, first you need to download the newest uploaded file. You must log in to your CodeCanyon account and head over to:
http://codecanyon.net/downloads
The safest way to update the plugin to a new version is via FTP Upload. Download the latest version, unzip the file, and copy the folder to your website wp-content/plugins/ overwriting the current plugin folder.