I need some help w/compositing issues
 

I'm recreating the explosion of the DeathStar from the Star Wars Special Edition Movie for my Special FX Final and I have a question; I'd love it if someone could answer before Friday. I need my explosion to be in the center of the Ring Of Fire (Concusion Effect), however, when I tried compositing it in AFX the Explosion is just sitting in the middle of the outer Ring; it is supposed to be inside of the outer ring. I hope I'm not too confusing anyone with this. How do I fix this Problem? Is it with Alpha Channels? If it is TELL ME HOW TO USE THEM FOR THIS REEEEEEEEEEEEEEEEEEELLLY FRUSTRATING ORDEAL. :banghead: :confused: :mad:
I attached a sample. This is not the final rendered image. It is just to show you guys the problem. I hope that you can see it. By the way this is the best site I been on since.......FOREVER!!!!!!

Sorry if this is too late, but yes, that is what the alpha channels do for you... (most of the time) :)

A poor workaround for your situation might be to make your own "alpha" in photoshop, and use that as a track matte for your fireball layer. ? maybe... not sure...

Next time, try rendering everything together, only use the "Background" shader on all of your "outer" particles or geometry, that way, your fireball alpha will make your fireball look as though it were inside....

Sorry if I sound so vague:(