creating content types and hook_node_info

Hello,

I'm creating a content type called which extends the basic node type by adding two date fields.

I don't understand how I notify Drupal of my content type. When I browse to node/add I can only see my content type when my hook_node_info function has module=>'node'. eg:

function exhibition_node_info() {
  return array(
    'exhibition' => array(
      'name' => t('Exhibition'),
      'module' => 'node',
      'description' => t("An exhibition (with start and end dates)."),
    )
  );
}

But this means my hooks get called when I don't want them to. I asume there is something that I am missing...

Can anyone point me in the right direction?

Thanks