The following video is the first in a 20-part WordPress 101 tutorial series by WP101.com. This video describes the elements of the WordPress Dashboard.
Note that most of these WP101 videos are not free, but you can pay for a plugin to install in your website that provides access to these videos. It can help you and users of your site to learn about WordPress, and seems to be quite popular. See the WP101 plugin site.