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: 
Check [projects on osflash](http://www.osflash.org/projects). All of these are free. There are IDEs, command line tools, editors, game servers, etc

...and check [tutorials](http://osflash.org/tutorials).
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.