Do you mean the orange button with the word Firefox that was in versions 4-28? That button was switched out and there's now a menu button on the right end of the toolbar, looks like a stack of 3 lines that some people call the "hamburger." This page shows where things moved between the menus:

http://jeffersonscher.com/res/menu/comp.php

If you want to restore the old button, you need to use an add-on. Please see this article: How to make the new Firefox look like the old Firefox.

"How do I get this button to work?" Sounds like it is working when you get "This is a secure Firefox page." when you click in the left side of the Location bar.

The rectangular orange Firefox button, that was used in Firefox 4 thru Firefox 28 is gone. Replaced (partially) by the 3-bar button on the extreme right-side of the Navigation Toolbar. Other menu items can be accessed via the Alt key or F10 key to show the traditional Menu bar with File, Edit, View, History, Bookmarks, Tools, & Help.

You see this orange Firefox button on the location/address bar instead of the "Site Identity Button" (globe/padlock) bar if you are on some built-in about: pages like the about:home page. You can set the home page to a different page or website if you want a home page with a regular globe/padlock.

• https://support.mozilla.org/kb/How+to+set+the+home+page