Review this series of articles and videos covering basic and advanced features and you’ll be an expert in no time. At a leisurely pace the entire series can be completed in less than 2 hours.
If you have any questions as you go through this series, please email support@axure.com.
Many of the articles contain videos. To view them, you will need Flash Player version 9 or higher.
AXURE 101: Introduction
Article 1: Introduction to Axure RP
Article 2: Annotated Wireframes
Article 3: Basic Interactions
Article 4: Masters
Article 5: HTML Prototypes
Article 6: Functional Specifications
Learn by Doing: Quick Start
A 30 minute step-by-step guide.
Guide:
AxureQuickStart.pdf 
RP File:
QuickStart.rp
AXURE 102: Flow Diagrams
Article 1: Flow Shapes & Connectors
Article 2: Generating Flow Diagrams
AXURE 201: Rich Interactions
Article 1: Dynamic Panels
Article 2: OnMouseEnter, OnMouseOut, and Rollover Effects
Article 3: Menus
AXURE 202: Rich Functionality
Article 1: Conditional Logic
Article 2: OnChange Event
Article 3: OnKeyUp Event
Article 4: OnFocus Event
Article 5: Variables
Article 6: OnPageLoad Event
AXURE 301: Maximizing Reuse of Masters
Article 1: Affecting Widgets in Masters
Article 2: Raised Events
AXURE 401: Collaboration
Article 1: Shared Projects