Adding taxonomy_image in a theme

I don't understand what files I need to modify to add the taxonomy_image in a theme.

I have found some documentation but I cannot do that it works, with so many versions and possibilities the explanation it's very segmented.

In the documentation talks about to add some code in the themes/theme/node.tpl.php, themes/theme/template.php or themes/engines/phptemplate/phptemplate.engine

If I add this code in the node.tpl.php file
print $taxonomy_images[0]

and this in the template.php

function _phptemplate_variables($hook, $vars) {
  if ($hook == 'node') {
    if (module_exist("taxonomy_image")) {
      foreach (taxonomy_node_get_terms($vars['node']->nid) as $term) {
        $vars['taxonomy_images'][] = taxonomy_image_display($term->tid, align='right' , alt='$term->name'");
      }
    }
  }
return $vars;
}

It don't work.

And I have seen this patch http://drupal.org/node/14028 to modify the phptemplate.engine, or put other codes in the node.tpl.php like this http://drupal.org/node/71704

Can somebody explain to me what files I must to modify for work in Drupal 4.7.3 with the phptemplate engine? I'm a newie with drupal :S