I take it you downloaded it from the
main website?
The first thing I can think of that you
might have done wrong, is that you downloaded the Source files instead of the program (which is labeled as just Download on the site). The source files need a special program to use them, presumably to edit them.
If that's not the problem, after you unzip the program and put the contents of the zip/rar file onto your computer, the editing program is in the Server folder.
If the editor program doesn't work for some reason, you need to download and install
this. There's instructions on how to install it on Vista on that page as well.
Hopefully this helps.
3nodding