To make something happen after a delay you need something to trigger it. In index.html find the second paragraph and put a new blank line after it. On that line put this:
<p onmouseup="document.write('NO!');">Tell the truth</p>
Save it. Load the page in the browser and click on the new paragraph.
<p onmouseup="">Tell the truth</p>
The HTML tells the browser that it should monitor the paragraph for mouse clicks (in a mouse click the button goes down then up). When the mouse button is released (onmouseup) it should do what is inside the double quotes.