How to update theme

Please tell me how to update to the latest Aqua theme. I have located the email of 9 July stating that there is an update available. When I click download it takes me to the Envato page where I originally downloaded the theme. Do I down load it to my computer and then upload it to my server as I did with the original theme or is there a way to do the update through wordpress? When I go into wordpress there is no notification that an update is available. Your prompt assistance would be appreciated. Thanks.