about what you're asking,check this out: UnFREEz 2.1 - WhitSoft Development
Try this freeware program which called unfreez,it's very easy to use;all what you need to do is drag your separated GIF you want to make as animated GIF
Note: for more info read the help manual(you don't need to it's to easy!)
But if you want more advanced program,you have to buy it,check this out: Easy GIF Animator - animated GIF editor - create and edit any gif animation
Note: there are many progs & ways to make GIFs, so don't just stick on these progs
I hope that I help you,so any comments just post it!