These documents are a useful collection of "How do I do x?" guides:

Basic Confluence Operations

• How do I upgrade to a new version of Confluence?
• How do I write Confluence pages in HTML?
• How do I delete unwanted "incoming links" from pages?
• How do I define structured content templates for pages?

Confluence and JIRA

• How can I best use Confluence and JIRA together?
• How do I make Confluence use my existing JIRA user database?
• How do I add a Confluence server to my existing JIRA standalone installation?

Hacks and Unsupported Modifications

• How do I change the look of the {gallery} macro?