1) Goto: http://gtk.php.net/download.php
2) Download "php-gtk-2.0.1 Windows binary pack"
3) Unzip into any folder. You are ready to go!
4) In case you have another php installed on your machine (e.g. you have a web server), to run php-gtk, you have to use the full path to the php in the folder you have unzipped in (3).
5) Suppose you have unzipped the php-gtk to c:\php-gtk, to run a php-gtk script,
a) create a command prompt
b) from the command prompt, type:
Try the above, and let me know if you bump into any problem.