You will need to start with Adobe Flash. There are also programming libraries for taking apart and putting back together swf files, however I don't think you'll need to go that route unless your planning on doing any flash game development for mobile phones. FYI iPhone does not support flash nor does android.
You want to get Flash, of course. I'd advise CS3 for starters (it's cheaper than CS4 and can help you get your feet wet along with having AS3 capability). You don't want to use the internal IDE though. FlashDevelop is very good for the coding aspect.
Flash CS4 for design(but most poeple use PS for design if i not mistake) if coding, use Flash CS4, Flex Builder or FlashDevelop(but flash Develop for Window only)
Lol. Looks like the OP is going to wish he did some basic research. Try googleing "flash game development ".
What you'll want is Adobe Flash (best version in my mind is CS4), and get a grasp of actionscript. Though the libraries are already in it, it's always a good idea to get some knowledge of actionscript to make creation a lot easier
Get FlashDevelop for the raw class development, get Charles Web Proxy for the web communication debugging, get Flash (CS3 is still my fav), and get an image editing app (photoshop/illustrator preferred) to develop your graphics