Consume Facebook API in PHP

Hello, I would like to consume the Facebook API in HP. I would like it to let me enter a Facebook page as such. I am new and I need to consume it either in PHP or in C#, the truth is that the code is taken, so I get an error. of

require_once(src/Facebook/autoload.php): failed to open stream on line 2, I hope you can help me, Thanks!

<? php require_once 'src/Facebook/autoload.php';
$fb = new Facebook\Facebook([
  'app_id' => '{id}',
  'app_secret' => '{contraseña}',
  'default_graph_version' => 'v2.2',
  ]);

try {
  // Requires the "read_stream" permission
  $response = $fb->get('/me/feed?fields=id,message&amp;limit=5');
} catch(Facebook\Exceptions\FacebookResponseException $e) {
  // When Graph returns an error
  echo 'Graph returned an error: ' . $e->getMessage();
  exit;
} catch(Facebook\Exceptions\FacebookSDKException $e) {
  // When validation fails or other local issues
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
  exit;
}

// Page 1
$feedEdge = $response->getGraphEdge();

foreach ($feedEdge as $status) {
  var_dump($status->asArray());
}

// Page 2 (next 5 results)
$nextFeed = $fb->next($feedEdge);

foreach ($nextFeed as $status) {
  var_dump($status->asArray());
}
?>