Hi Steve Odem,
If you downloaded the file from a web page, it most likely went into a Downloads folder on your computer. If you don't know where that folder is, the easiest thing to do may be to use the Find feature of Mac OS or Windows (whichever you use), to search for the PDF form. Once you know where the file ended up, you can easily navigate to that folder in Reader. (Choose File > Open in Reader, then navigate to the file in the Open dialog box.)
Please let us know if you have additional questions.
Best,
Sara