Flash can be bought for 800$ on Adobe's website. There's also a free trial version here.
Of course, you could pirate the thing and get it for free, but how could you live with not giving 800 bucks for a drawing software ?
Also, Flash is only needed to make animated imports (the swf ones).
You should start by making still ones (the png imports) with drawing softwares like gimp and photoshop.