How do I print main_menu?
You can do it both ways:


You can add menu block to your template - just like any other block (this method is the easiest).
If you need more customization, you can do it in template:


page.tpl.php

&lt;?php if ($primary_nav): print $primary_nav; endif; ?&gt;


template.php

if (isset($variables['main_menu'])) {
  $variables['primary_nav'] = theme('links__system_main_menu', array(
    'links' =&gt; $variables['main_menu'],
    'attributes' =&gt; array(
      'class' =&gt; array('links', 'inline', 'main-menu'),
    ),
    'heading' =&gt; array(
      'text' =&gt; t('Main menu'),
      'level' =&gt; 'h2',
      'class' =&gt; array('element-invisible'),
    )
  ));
}
else {
  $variables['primary_nav'] = FALSE;
}