I suggest you find a tutorial on line about flash basics. Google keywords "flash tutorial"
If your template came with some form of Read Me file, you should start there. A good template design will provide instructiuions on how to modify it to include your own content. Beyond that, if it is a Flash site, then you want to edit Flash files that have .fla extensions. There may be data files that came with the template that may have .xml or .txt extensions. You may want to look thru these to see if the resemble/define any of the content you plan to change.
Unfortunately, if there are alot of files that came with your template then there are alot of possibilities as to what files need to be dealt with in what way. If there is no read me file, then open whatever fla file came with it and see what's in it that you planned to change as a starting point.