How can I load a javascript file into a Drupal 7 page using the Code per Node module?
Code per node module is  intented to use to have a custom JS for each node. The JS code must be placed inline, in the node add / edit form. You have this tutorial to see how it works.

If you want to add the same js to a specific content type you can create a module custom where you invoke preprocess node hook:

function YOUR_MODULE_preprocess_node(&amp;$variables) {
  if ($variables['type'] == 'INSERT_CONTENT_TYPE') {
       drupal_add_js('path/to/somescript.js');
  }
}


You can also do this in a custom theme, there are examples in this answer.

If you want see a module with drupal_add_js examples and a nice documenttion, you can see the module js_example , which is a module inside Examples 7.x.