Forum:How do I create a JavaScript extension on here with code?

Hello, guys and gals. I want to create a JavaScript enhancement for Wikia on here. How do I do so? Do I need to create a page, or is it more complicated than that? I want it to show the JavaScript code in its proper format. Somebody help me. Thanks!

TheFallenOneGOTH of the Fallen Kingdom (Talk, Contribs) 17:56, July 10, 2014 (UTC)