I'm new to PHP and since I'm setting up a website using Joomla 2.5, I need some basic understanding of PHP. But when I run the following code, from a book I'm using as a intro text, nothing is displayed on Firefox (version 18).

<head><title>PHP says hello</title></head>
echo "Hello, World!";
I've checked out phpinfo() to the extent of my limited understanding and I can't see anything obviously wrong.

Any help would be much appreciated