Customize admin content type page design
See Drupal 7 Template (Theme Hook) Suggestions

You can do something like page--node--edit.tpl.php or page--node--1.tpl.php

See the available variables in page.tpl.php

Also you can try hook_preprocess_page

&lt;?php
function themeName_preprocess_page(&amp;$vars, $hook) {
  if ((arg(0) == 'node') &amp;&amp; (arg(1) == 'add' &amp;&amp; arg(2) == 'product')) {
    $vars['template_files'][] =  'page-node-add-type';
  }
}
?&gt;