So the error is the paragraph is not changing while we load the page.
Here is the code, I have added the JavaScript in the head itself. I even tried using external JavaScript too but that didn't work either. I used the onload function of JavaScript to change my inner HTML of paragraph, but it did not work.
<html>
<head>
<script type="text/JavaScript">
function fun_name() {
alert("Working");
document.getElementById("para").innerHTML = "After Loading"
}
</script>
</head>
<body>
<p onload="fun_name();" id="para">Before Loading</p>
</body>
</html>