Let's look at an example. In this example I create a modal popup. Modal meaning that it takes control of the window not allowing you to interact with the background page until the popup is closed. To be able to use the jQuery functions you must include the relevant jQuery libraries and stylesheets. Pay attention to the version that you need to use. In this example I used the latest version 1.4.2. You can download and host the library yourself or you can use a publicly accessible library for example from Google. Once you become familiar with the syntax and what the library offers then following the documentation or examples and customising to suit is painless.