Hello. This is a really newbie question but I haven't done coding in a while and got stuck. The Visualforce Basics trailhead says to Open your browser’s JavaScript console and enter the following code for format your Visualforce page with Lightning.

$A.get("e.force:navigateToURL").setParams(
    {"url": "/apex/pageName"}).fire();

I know how to get to the Chrome DevTools, but how do you run Javascript inside it?