Doing a Google search for "gd windows" shows Gd for Windows as the first result. That page provides a link to download the binary installer to install GD on a Windows system. I would recommend trying that route for installing GD.

Alternatively, if you're willing to use a different Perl distribution, Strawberry Perl's 5.20.3.1 32-bit release already includes the GD module (see the release notes).