writing-csv what is wrong with my code? Permission denied

<?php

$new_person = [
  filter_input(INPUT_POST, 'first', FILTER_SANITIZE_STRING),
  filter_input(INPUT_POST, 'last', FILTER_SANITIZE_STRING),
  filter_input(INPUT_POST, 'website', FILTER_SANITIZE_URL),
  filter_input(INPUT_POST, 'twitter', FILTER_SANITIZE_STRING),
  filter_input(INPUT_POST, 'img', FILTER_SANITIZE_URL)
];

if (($fh = fopen('../data/csv/people.csv', 'a+' )) !== false) {
  fseek($fh, -1, SEEK_END);
  if (fgets($fh) != PHP_EOL) {
    fputs($fh, PHP_EOL);
  }
  fputcsv($fh, $new_person);
  fclose($fh);
}
header('location: /people.php'); 

<?php
/**
 * Form for adding more people to the csv file
 * first,last,website,twitter,img
 */
$title = 'Add Person';
require 'inc/header.php';
?>
<form method="post" action="inc/write_csv.php">
    <div class="form-group input-group-lg">
        <label class="control-label" for="first">First Name</label>
        <input class="form-control" type="text" name="first" id="first" />
    </div>

    <div class="form-group input-group-lg">
        <label for="last">Last Name</label>
        <input class="form-control" type="text" name="last" id="last" />
    </div>

    <div class="form-group input-group-lg">
        <label for="website">Website</label>
        <div class="input-group input-group-lg">
            <span class="input-group-addon" id="website-addon">http://</span>
            <input class="form-control" aria-describedby="website-addon" type="text" name="website" id="website" />
        </div>
    </div>

    <div class="form-group input-group-lg">
        <label for="twitter">Twitter</label>
    <div class="input-group input-group-lg">
        <span class="input-group-addon" id="twitter-addon">@</span>
        <input class="form-control" aria-describedby="twitter-addon" type="text" name="twitter" id="twitter" />
    </div>
    </div>

    <div class="form-group input-group-lg">
        <label for="img">Image</label>
        <input class="form-control" type="text" name="img" id="img" placeholder="http://" />
    </div>

    <button class="btn-lg btn-default" type="submit"><?php echo $title; ?></button>
</form>
<?php
require 'inc/footer.php';