#!/usr/bin/perl
use strict;
use warnings;
use WWW::Mechanize;

my $mech = WWW::Mechanize->new();
$mech->get('https://derpderpderp.com'); # fake URL
$mech->click_button( number => 2 ) # click the second button on fake page
#do whatever you want with the next page, e.g. print the title
print $mech->title;