You are using 3 different languages.
That code you pasted is HTML and CSS. I suggest in the future you use CODE tags when pasting code.
Add this line to the top of your page header.
You will then need to learn CSS, and create a new file called "style.css".
<!-- doctype !-->
<title><!-- title !--></title>
<link rel = "stylesheet" href = "style.css" type = "text/css" />
--- rest of your page ---
Something to get you started: