how can I use or run a php sample?

hi, I have been making some tests. I want to learn PHP. But I have not achived to run a php sample like below. Actually I want to make a mail sender on my web page with php. I have found a sample about it but I couldn't run it so I decided to learn php as far as possible. <html> <head> <title>Example</title> </head> <body> <?php echo "Hi, I'm a PHP script!"; ?> </body> </html> (I save it above code as html, but it have not run. also when I run a .php file directly by writing adress bar n explorer it have not run only It was seemed as text.) I am raw and new at this topic. I need information begining to first. I have searched thoroughly internet but I confused. Should I install php or apache or some other program on my system in order to use PHP code in my web pages? Could you help me please? How can I start for learning php? thanks. my system w2000 professional and Internet service manager is installed