如何执行php代码[关闭]

I need some explanations for how to execute the following PHP code. I am using Notepad++ & wamp server. All of files.php are to same directory.

Thanks ///////////////////////////////

index.php
//////////////////////////////
<?php  
require("decide-lang.php");  
?>  
<html><title>Exercice </title>  
<body>  
<?php echo TXT_INDEX; ?>  
<p><br>
  News: <?php echo TXT_NEWS; ?> <br>
  Conseil du jour: <?php echo TXT_CONSEIL_INDEX ; ?> </p>
<p>&nbsp;</p>
<p><a href="index.php?lang=en">Not french??</a></p>
</body>  
</html>  


//////////////////////////////
decide-lang.php
//////////////////////////////
<?php  
if ($lang=='fr') {           // si la langue est 'fr' (français) on inclut le fichier fr-lang.php  
include('fr-lang.php');  
}   
else if ($lang=='en') {      // si la langue est 'en' (anglais) on inclut le fichier en-lang.php  
include('en-lang.php');  
}  
else {                       // si aucune langue n'est déclarée on inclut le fichier fr-lang.php par défaut  
include('fr-lang.php');  
}  

?>  

//////////////////////////////
en-lang.php
/////////////////////////////
<?php  
define('TXT_INDEX', 'Welcome on YOu_Site.com!');  
define('TXT_NEWS', 'The sun is shining !');  
define('TXT_CONSEIL_INDEX', 'Lets do some PHP !');  
?> 
//////////////////////////////
fr-lang.php
/////////////////////////////
<?php  
define('TXT_INDEX', 'Bienvenue sur votre_site.com !');  
define('TXT_NEWS', 'Il fait un soleil radieux !');  
define('TXT_CONSEIL_INDEX', 'Faites du PHP !');  

?>

  1. Run your php file in a web server: http://localhost/index.php

  2. Run you php file on the command line: >php index.php

  1. Put your .php files in htdocs folder of wamp.
  2. Run your wamp.
  3. Open a web browser.
  4. Go to http://localhost/yourFile.php

Note 1: If you have a file named index.php, you can goto http://localhost/ to see that

Note 2: You can make a folder in htdocs folder and name it as your project, so you may go to http://localhost/myProject/myfile.php