I have a .swf file with an email field and I want to add my opt-in code to that email field so that when visitors enter their email they will be subscribed to my list on Mailchimp. I never worked with .swf files before and I have no idea where to start.
You can’t edit the swf without the source. You might be able to decompile the swf and rebuild an fla from that but that can also cause problems of its own.