If you didn’t configure Envato Market auto-updates plugin (it’s recommended) you can update theme and plugins manually as follows:

  1. Go to your downloads section on ThemeForest http://themeforest.net/downloads and download theme (Installable WordPress file only) – it will be the lastest version.
  2. Extract the zip file and upload all files (overwrite old files) on your server to
  3. After uploading new version of theme you also have to update plugins. You will see a list of plugins that require update in Appearance → Install Plugins.

You won’t loose any content or settings, but if you’ve made any customizations to source files they will be lost, so please use Child Themes http://codex.wordpress.org/Child_Themes to modify theme .php files. 😉