Class not found

[bogey]

Windows 8
XAMPP 1.8.1
Apache 2.4.3
MySQl 5.5.27 (Community Server)
PHP 5.4.7 (VC9 X86 32bit thread safe) + PEAR
OpenSSL 1.0.1c
XAMPP Control Panel v3.1.0 3.1.0

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1. I am searching for a way to make documented functions or methods usable in my code.

2. I am familiar with the "using" statements in C#.
Is there something like that in PHP?

3. What are the groups of Namespaces or, something else, to give me access to
documented Classes, methods, or functions?

4. There are many other Classes and methods I have tried and failed.
Is there a default setting in php.ini I need to change?

5. Aside from the above, I wrote a namespace and used it.
Is this knowledge relevent to the above problem?
redirect.php

6. Thank you for your patience.
--------------------------
<?php
HttpResponse::redirect('./prog1.php', FALSE);// results in Fatal error: Class HttpResponse not found.
?>
<?php
redirect('./prog1.php', FALSE);// results in Fatal error: Call to undefined function redirect()
?>

++++++++++++++++++++++++++++++++
prog1.php
-----------------------------------------------------------------------------------------------------
<?php
namespace included;// requires this and the following statement to work.
include 'included.php';

$string = "default";
$instance = new test($string);

$string = "Is this valid";
$string = $instance->test($string);
echo $string;

?>
+++++++++++++++++++
included.php
-------------------------------------------------------
<?php
namespace included;
class test
{
public function test($string)
{
$string = $string . " Success";

return $string;
}
}
?>
++++++++++++++++++++++++++++++++++++++++
Output:
Is this valid Success