Question: I have Flash files that I would like to make edits on but I don't know how or with what.

Is there some software that can edit a Flash (.fla) file?

(Ideally something free.)

Answer: 
You can download the 30-day trial version of [Adobe Flash Professional](http://www.adobe.com/products/flash/). I don't know of any free alternative that works as well.
there are no legally free programs that allows full capable editing of Flash source files (.fla). Only Adobe Flash (not Player!) can do it.

I suggest you stop wasting time hoping a free program like this comes along, and start using that time saved to work and buy a copy eventually.