Let me see if I get it: you have a Flash template but it's a SWF file, not an open editable FLA file and wants to change the text inside?
Maybe you should start by letting us know where you got this template from, the URL to it so we can take a look and see what it does, etc. It may be simpler than it looks.
A brief overview on Flash will not help you if you don't have th FLA file. And if you have the FLA file you do not need a decompiler...
So... I really don't know what you need or want at this point.
Please, help us help you.