This should get you up and running....

#!usr/bin/perl

use strict;
use Tk;

my $top = MainWindow->new;  
my $color = qw/Green Blue Yellow Red White/;
my @wb;
$wb[0] = $top->Radiobutton(
    -variable => \$color,
    -command  => [\&cb_rbutton, $top],
    -text     => 'Green',
    -value    => 'green')->pack(
    -side     => 'top',
    -anchor   => 'w');
$wb[1] = $top->Radiobutton(
    -variable => \$color,
    -command  => [\&cb_rbutton, $top],
    -text     => 'Blue',
    -value    => 'blue')->pack(
    -side     => 'top',
    -anchor   => 'w');
$wb[2] = $top->Radiobutton(
    -variable => \$color,
    -command  => [\&cb_rbutton, $top],
    -text     => 'Yellow',
    -value    => 'yellow')->pack(
    -side     => 'top',
    -anchor   => 'w');
$wb[3] = $top->Radiobutton(
    -variable => \$color,
    -command  => [\&cb_rbutton, $top],
    -text     => 'Red',
    -value    => 'red')->pack(
    -side     => 'top',
    -anchor   => 'w');
$wb[4] = $top->Radiobutton(
    -variable => \$color,
    -command  => [\&cb_rbutton, $top],
    -text     => 'White',
    -value    => 'white')->pack(
    -side     => 'top',
    -anchor   => 'w');
         
Tk::MainLoop();

sub cb_rbutton {
    my $rb = shift;
    print "$color is on\n";
    return;
}
[download]