Ok, I recommend taking a look around google for some advice on books. If you're planning on starting now I'd recommend starting with ActionScript 3, it's the most recent edition of the language and you won't be able to make iPhone packager apps with the older versions.
It shows you how to build a basic shooter, although I'd recommend further reading as there are a few bugs in this tutorial. It's a decent place to start!
Also buy his book, it's more or less tailored to people just starting out with flash games, covers all bases very well and it's all ActionScript 3 based.