The Confluence User's Guide is for project managers, developers, testers – anyone who uses Confluence. New to Confluence? Start by exploring the Confluence dashboard and learning about spaces, pages and blog posts. Try creating a new space, then add a page to that space, add some content and a comment to that page and then export the page to PDF.
The Confluence Administrator's Guide is for people with Confluence administration rights. It will help you set up users and groups, security for users, groups and spaces, and keep track of any changes and updates made within your Confluence site. You may want to customise the look and feel of Confluence, by applying a theme to a space or modifying colour schemes and layouts. Admin tasks such as backup are also covered. You may also find the Knowledge Base, FAQ and Atlassian Answers useful.
The Confluence Installation Guide is for people who are installing Confluence for the first time. Check the requirements and supported platforms, then download and install Confluence. Where to next? The Confluence 101 will help you get started. When setting up Confluence, load the Example Site ('Demonstration Space'), which contains a tutorial and additional content to help you get familiar with using Confluence. If you are using other Atlassian products, take a look at the Integration Guide.
The Confluence Upgrade Guide is for people who are upgrading their instance of Confluence. Start by reading the latest Release Notes, the Upgrade Notes Overview and version-specific Upgrade Notes for the version to which you are upgrading. Then, download Confluence and follow the main Upgrade Guide.
These resources are for software developers who want to create their own plugins for Confluence. Take a look at the Confluence developer documentation and the API documentation. You may also find Confluence development topics on Atlassian Answers useful.