First you need to say that since AS3, flash wonderful free reference base, the best of those with whom I am familiar. So you should start with her. The first thing you should address, even if you know nothing is a book (available in Russian) "PROGRAMMING ACTIONscript 3.0" (http://bit.ly/9oRs6H
). After reading it, you will be able to write polnochnye application.
Next you need to decide on the authoring tool. If you are an animator, it is more convenient adamowski Flash CS, probably nothing. But, if you are a programmer, here is available a fleet of free and paid means. This Powerflasher FDT (surcharge), and Realaxy Actionscript Editor from tectonic developers and free SEPHY. But my favorite is FlashDevelop, a free editor based on Eclipse, reliable, easy, fast and produmanny to detail, in General, must see.
And I would not advise to begin learning with Flex — it's like eating dumplings with hands. It seems comfortable, but will constantly be uncomfortable. Not to mention the fact that Flex is the application development tool with a user-interface, its code is translated into as3, and then compiled.
Still can go https://freeriatools.adobe.com/
to say that you are a student and get the licensed version of Flash Builder for non-commercial use.