how to write css in html

CSS
<link rel="stylesheet" href="styles.css">  <!DOCTYPE html>
<html>
<body>

<h1 style="color:blue;text-align:center;">This 
  is a heading</h1>
<p style="color:red;">This is a paragraph.</p>


  </body>
</html> <p style="color: blue; font-size: 46px;">  <link rel="stylesheet" href="PathToYourFile.css">
Source

Also in CSS: