This tutorial will help you get started with Confluence:
What is a space?
A space is an area within Confluence, containing your wiki pages. You can think of each space as a sub-site, or mini-site, each with its own home page.
What is the Dashboard?
The Dashboard is the home page of your Confluence wiki. The Dashboard contains a list of all the spaces within your wiki, as well as a list of recently updated content.
What is a wiki?
A wiki is a piece of software that allows you and your colleagues to create and edit web pages quickly and simply. Just click, edit and save. Content is published immediately.
What is Confluence?
Confluence is an enterprise wiki with some extra communication tools, including news items (blogs) and RSS feeds.
What makes Confluence an enterprise wiki?
Different organisations use Confluence for different purposes: as a company intranet, corporate website, project workspace, knowledge base, documentation site and a host of other implementations. All these are made possible by Confluence's enterprise-appropriate features, including: security permissions at the page, space and site level; content structuring and restructuring options; LDAP compatibility and more.
If you prefer, you can see the whole tutorial on one page.