$package_name = $operatingsystem ? {
                 debian  => 'apache-for-debian',
                 redhat  => 'apache-for-rhel',
                 default => 'apache',
}
package{$package_name: ensure => installed}

file{'my_script':
      ensure  => file, #as opposed to directory
      path    => '/path/on/client/myscript',
      mode    => 0755,
      source  => 'puppet:///path/on/server/myscript',
}