I would break your learning down into these topics, in order of priority. A Google search or look through the documentation will explain each in adequate detail.
- Language basics
- Operators.
- Statements, Keywords & Directives.
- Top level functions and classes.
- Storing data in Objects, Arrays & Vectors.
- Garbage collection.
- The display architecture.
- The document root.
- The Stage.
- DisplayObjects and DisplayObjectContainers.
- Creating library symbols and exporting them for ActionScript.
- The Event model.
- Listening for and reacting to events.
- Dispatching events.
- Object Oriented Programming.
- Creating a document class.
- Defining classes.
- Creating instances of classes.
- Building relationships between class instances.