Flex：如何导入.zip项目？

Whenever you view a flex app and go to view source you can download a zip of the flex app. Once you do that how do you import it? I went to flex>import and I get to options import archive file I pointed that to the zip and it says its not a valid archive file. so I tried the other option import flex project folder, I extracted the zip and pointed it to that and it says its not a valid project folder...what am I supposed to do?Whenever you view a flex app and go to view sou