Как добавляются поля в форму регистрации

//============================================================================//
//============================= Загрузка аватара  ============================//
//============================================================================//
if ($do=='avatar'){
 
	if (!$inUser->id || ($inUser->id && $inUser->id != $id)){ cmsCore::error404(); }
 
	$inPage->setTitle($_LANG['LOAD_AVATAR']);
	$inPage->addPathway($inUser->nickname, cmsUser::getProfileURL($inUser->login));
	$inPage->addPathway($_LANG['LOAD_AVATAR']);
 
	if (cmsCore::inRequest('upload')) {
 
		cmsCore::loadClass('upload_photo');
		$inUploadPhoto = cmsUploadPhoto::getInstance();
		// Выставляем конфигурационные параметры
		$inUploadPhoto->upload_dir    = PATH.'/images/';
		$inUploadPhoto->dir_medium    = 'users/avatars/';
		$inUploadPhoto->dir_small     = 'users/avatars/small/';
		$inUploadPhoto->small_size_w  = $model->config['smallw'];
		$inUploadPhoto->medium_size_w = $model->config['medw'];
		$inUploadPhoto->medium_size_h = $model->config['medh'];
		$inUploadPhoto->is_watermark  = false;
		$inUploadPhoto->input_name    = 'picture';
 
		$file = $inUploadPhoto->uploadPhoto($inUser->orig_imageurl);
 
		if(!$file){
 
			cmsCore::addSessionMessage('<strong>'.$_LANG['ERROR'].':</strong> '.cmsCore::uploadError().'!', 'error');
			cmsCore::redirect('/users/'.$id.'/avatar.html');
 
		}
 
		$sql = "UPDATE cms_user_profiles SET imageurl = '{$file['filename']}' WHERE user_id = '$id' LIMIT 1";
		$inDB->query($sql);
		// очищаем предыдущую запись о смене аватара
		cmsActions::removeObjectLog('add_avatar', $id);
		// выводим сообщение в ленту
		cmsActions::log('add_avatar', array(
			  'object' => '',
			  'object_url' => '',
			  'object_id' => $id,
			  'target' => '',
			  'target_url' => '',
			  'description' => '<a href="'.cmsUser::getProfileURL($inUser->login).'" class="act_usr_ava">
								   <img border="0" src="/images/users/avatars/small/'.$file['filename'].'">
								</a>'
		));
 
		cmsCore::redirect(cmsUser::getProfileURL($inUser->login));
 
	} else {
 
		cmsPage::initTemplate('components', 'com_users_avatar_upload')->
                assign('id', $id)->
                display('com_users_avatar_upload.tpl');
 
	}
}