Answer:
I don't quite understand the question. If you mean "create page in HTML", see image 2. If you mean "create script that is placed in the HTML page", see image 1
HTML is not a programming language. It is a markup language. You should write scripts in JavaScript or other programming languages.
1
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<h1>Hello world!</h1>
<*cript>
function paint() {
document.querySelector("h1").style.color = "brown";
}
setTimeout(paint, 2000)
</*cript>
</body>
</html>
2
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<style>
h1 {
color: brown;
}
</style>
</head>
<body>
<h1>Hello world!</h1>
</body>
</html>