If you want to install a perl module in a specific directory that you have write access to (instead of the default system dirs) you could start with something like:

# unpack the tarbal and cd to the created directory (the one containin
+g Makefile.PL)
> LIB=$HOME/lib perl Makefile.PL
> make
> make test
# check to see if the tests are successful
> make install
[download]

This should install the perl module into $HOME/lib. If you want to use the module, you should make sure $HOME/lib is in the module include path. One way to do that is to put use lib "$ENV{HOME}/lib"; before the use GD; line.

Note that you should ALWAYS try to install modules by using the perl Makefile.PL ... make install route unless you can't - lots of modules require more than just copying to configure them for your system - for one thing, like GD, many require a translation and compilation of XS code (this also means you will need a C compiler to create those modules).

update: see also perlfaq8 and ExtUtils::MakeMaker