I don't normally use javascript, but I'm writing a script for greasemonkey to extend a specific page on stumbleupon.com.
Basically, I've just started, and I'm trying to add a textbox to the page.

Code:
// ==UserScript==
// @author         Francis Stokes
// @name           Recent Shares Ext.
// @namespace      rse
// @description    Extension to the stanndard Recent Shares Page
// @include        http://*.stumbleupon.com/shares/
// ==/UserScript==

var tb = document.createElement('input');
tb.setAttribute("type", "text");
var f = document.forms[0];
f.appendChild(tb);
No textbox in sight. I don't think Im doing it right.
Any corrections would be helpful.