PHP is a server-side scripting language designed for web development, it's very flexible in terms of what you can do with it.
For it to work on your PC I recommend you install EasyPHP , it has everything needed to get you started like, Apache 2 web-server and Mysql 5.5, that is a database required for more complex PHP scripts to work.
After installing EasyPHP, you can now open a Notepad and test how are things going by typing, for example :
<?php echo "It works!"; ?> .After you can go ahead and click: File > Save as > demo.php ,while making sure you set the Save as type to "All Files".
Now you can go to your browser and open "demo.php" with it. You should be able see the text "It works!"