Heh, don't worry, it's not your fault i actually don't want to put what i use because i don't want people to think thats what one HAS to use. Really, it doesn't matter if you have fancy programs like After Effects, you improvise with Photoshop or you just draw on a stack of paper and scan it in
I just draw straight onto GIMP (Which is free) and edit in After Effects (Which'll cost a battleship and a half... but the editting i do for icons and things like my Tank are minimal) GIMP can make animated .gif images and MonkeyJam (which is also free) can make movie files in the form of a .avi. Windows Movie Maker can also composite the seperate .avis into a much larger movie if you're creating something really big and these 3 free pieces of software were all i used to make the animation "The Dragon, Griffin and Chimera"
I draw everything in GIMP (Or sometimes Photoshop or Sai, save the images and import as neccessary) Just have all your frames in order as they should be and save as a .gif, it'll do it automatically for you