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Unzip all files to a folder in your wp-content/plugins directory, go to the plugins page in your admin panel and activate it.

To use the widget, go to presentations page and simply drag it onto the sidebar.

If you do not want to use the widget, use one of the functions hh_recently_updated_posts() or hh_rup_get() which will print the posts as HTML UL or return a PHP array respectively. Also have a look at the 'parameters' section.