Maybe take a look at the win32-gui-demos.pl script which comes with Win32::GUI. It's a handy little program that allows you to view the sample scripts that also come with Win32::GUI. You can view the source of the scripts (including itself) as well as run them. These scripts should provide some good examples for using Win32::GUI and should help you on your way.
Yes, the documentation is a bit sparse. If you know what you are looking for, you can usually find information in the Microsoft MSDN Documentation Library, but that requires knowledge of the underlying Windows functions that Win32::GUI uses. Check out the source for Win32::GUI if you are keen.
And if you are still stuck, you can always ask for help on PerlMonks :)