Displays a list of RSS/Atom feed items given the feed URL and other parameters (optionals). Highly customizable.
The easiest way is: from Plugins of your wordpress administration, select "Add new", search for "RSS just better" into the search text-box then click on 'Install' (on the right) when prompted with this plugin
you can download this plugin from wordpress repository, unzip it (a directory with 5 files will be extracted) and upload it to the '/wp-content/plugins/' directory of your wordpress administration.
Activate the plugin through the Plugins->Installed Plugins menu in your WordPress administration
Use it! (see Usage in Other Notes)