how to create your own module

[itshardtogetone]

Hi,
I am using windowsXP and I have my perl installed in c:\perl
I wish to write my own module and so I wrote a simple module and saved it in 
c:\perl\site\lib\mymod.pm but when I ran myscript below, nothing was printed 
out and the error msg was "Global symbol "@a" requires explicit package name at 
testing.cgi line 6. Execution of testing.cgi aborted due to compilation 
errors." so what must I do.
Thanks

### my mod.pm ######
#!/usr/bin/perl
use strict;
use warnings;

package mymod;
require Exporter;
my @ISA = qw(Exporter);
my @EXPORT = qw();
my @EXPORT_OK = qw();

my @a = qw(1 2 3);
@EXPORT_OK = qw(@a);

######################
#### testing.cgi#########
#!/usr/bin/perl
use strict;
use warnings;
use mymod qw(@a);

my @a = @a;
print @a;