One of the reasons EWU is utilizing WordPress is the great support from the user community. With EWU's limited resources, we'd never be able to maintain documentation with the same level of quality as the WordPress user community does.
One community supported resource that is great for both new and experienced WordPress users is the WordPress Codex, an online manual for WordPress and a living repository for WordPress information and documentation.
We've added some EWU customization to WordPress that may change small pieces of your WordPress experience, but the Codex in general will cover 90% of your WordPress needs. It's a great place to start learning more at your own pace.