The plugin offers you the possibility to easily manipulate important metadata, gain insight to the SEO status of various aspects of your site and how improve them.
In addition, the plugin automatically performs grunt operations that are vital for good SEO, such as sitemap creation and pinging.
To put it short, with Open WordPress SEO search engines find your content more easily, index your content faster, and give your site better ranking.
The easiest way to install the plugin is from WordPress admin control panel. Go to Plugins → Add new, search for Open WordPress SEO and click Install now. Then activate the plugin from the plugins list.
Free download (.zip archive) is available via WordPress.org plugins portal. Download the file and extract the folder to your plugins directory. Then activate the plugin on control panel's Installed Plugins section.
After activation it is recommended to head to plugin settings and go through the basic options. It only takes a couple of minutes and is well worth it.
If you have issues with the plugin or need help to use it please send message via WordPress support portal.
All messages there will be responded to. Thanks!