Create the CSS File:
Save it with a .css extension.
.css
Example: style.css
style.css
write your css rules in styles.css
Create or Open the HTML File:
Save it with a .html extension.
.html
Example: index.html
index.html
locate the section
This links the CSS file to your HTML.
Use the Tag Inside the Section:
html>
<html>
<head>
<title>My Web Page</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<h1>Hello, World!</h1>
</body>
</html>