See A Guide to Installing Modules. But I'm not sure that X11::GUITest will work on Windows, as Windows does not have an X11 server, and X11 is usually used on Unixish operating systems. But if you have an X11 server installed, that will maybe do what you want. Upon further inspection, the X11::GUITest module needs a working C compiler installed. So you should look for a premade ppm or install the matching C compiler for your Perl.