Display user nodes

I am new at programming Drupal. I am trying to create a module that display the users nodes.
If I am going at it the wrong way, let me know.

Here is my displaynode.info file:

; $Id$
name = "displaynode"
description = "Display nodes created by user"
;dependencies[] =
core = 6.x

Here is my "displaynode.module" file:

<?php
// $Id$

/**
* Implementation of hook_perm().
*/
function displaynode_perm() {
return array('view displaynode');
}

/**
* Implementation of hook_menu().
*/
function displaynode_menu() {
$items['admin/settings/displaynode'] = array(
'title' => 'displaynode',
'description' => 'Display the user node',
'page callback' => 'drupal_get_form',
'page arguments' => array('displaynode_nodeapi') ,
'access arguments' => array('administer site configuration'),
'type' => MENU_CALLBACK,
);
return $items;
}

/**
* Implementation of hook_nodeapi().
*/
function displaynode_nodeapi() {
global $user;

switch ($op) {
    case 'view':
        // query to execute
        $sql = "select nid from node where uid = %d";
        $result = db_query($sql, $user->uid);

        $output = "";

        while ($node = db_fetch_object($result)) {
          $output .= node_view(node_load($node->nid), true);
        }

    break;
}

print $output;

}

When I go to "admin/settings/displaynode", all I get is the "admin/settings" page.
Can some one give me an idea of what am I missing?

:-)