If you want to get into programming I would suggest avoiding ActionScript. It does what it does well, but it is designed more to empower regular designers than to be a good programming language.
If you just want to go for flash games go for it, if you want to learn general programming pick something else.
If you're going for Lua, it's just about the best possible first language.
Also, see this :)
https://powdertoy.co.uk/Discussions/Thread/View.html?Thread=17801
Well, then learn Flash!
Although Flash is a bit expensive :/
If you want to make something like flash, learn Javascript (and the processing.js library). With js/processing, you can make programs similar to Flash apps.
You can learn the most basic stuff at khanacademy.org, in their Computer Science section.