If you have installed and activated Envato ToolKit plugin which comes packed with the theme, on your wordpress admin you should be able to see a menu with the same name.
Click on it to to go to the plugin settings page, wher you need to enter your themeforest user name and a secret API key which you can easily genrate one by loging into your themeforest account, then go to Settings → Api Keys, then enter a label for your API key and click onGenerate API Key button.
That is all you have to do, from now on, whenever I release an update for the theme on themeforest, you be be notified on your own wordpress admin and you can easily update the theme to it’s latest version by clicking a button.
Important: After updating the theme, if in your theme options panel, if you have customized the options under color/type/styles you need to re-save your options to reset the dynamic.css file with your options. You will not loose your options after theme updates, you just have to re write the options in your dynamic.css file bu re-saving the options.