The Advanced Custom Field Widget is an extension of the Custom Field Widget by Scott Wallick, and displays values of custom field keys.
Installing this plugin, is just like installing any other WordPress plugin.
/adv-custom-field-widget/folder from the archive
In other words, just upload the
/adv-custom-field-widget/ folder and its contents to your plugins folder.
For more information about plugins and installing them, please review the managing plugins section of the WordPress Codex.