The website http://support.wordpress.com has a huge amount of information to get you going. Below is an excellent starter guide to WordPress.
If you prefer to listen rather than read, WordPress.tv offers help in video format (http://wordpress.tv)
Another easy form of help in text format is to be found at http://faq.wordpress.com This frequently asked section (FAQ) is a great resource.
FAQs are also organized in easy to read questions like the ones below
If you cannot find what you are looking for there is always the trusty old search button