Here is a short video, that will teach you about the basic functions in WordPress.

The video begins with a guide of how to download WordPress. If you want to skip that part, start the video at 0:44. If you already have a WordPress account, you can start the video at 1:21. Then you will learn about posts, sites, pictures, themes, plugins, users and URL settings.

To learn more about making your blog, like changing it’s theme, please check out the excellent beginners guides at the WordPress Codex and at WordPress.tv