How to use CSS?

I created a simple CSS file. and save it as "background.css" under the same folder of my application.

hr {color: sienna}
p {margin-left: 260px}

body {background-image: url("images/background.gif")}

But I'm unable to use it when my web file has the extension of .fwx.

It works well when you link it using .html file format.

<head>

</head>

Regards.