Hello, World

Try following expressions :

$('h1').text('Hi, there.');	$('h1').html('hello,<br>world');	$('h1').slideUp();	$('h1').slideDown();
$('ul').css('color', 'red');	$('ul :first-child').css('color', 'yellow');	$('ul :nth-child(3)').css('color', 'blue');	$('#2nd').css('color', 'blue');
$('#1st').text($('h1').text());

With use of the JavaScript Console of Google Chrome is recommended.
Press Shift + Control + J to show the console.

The HTML document of the demo above is,

<h1>Hello, World</h1>
<ul>
<li id="1st">item 1</li>
<li id="2nd">item 2</li>
<li id="3rd">item 3</li>
</ul>