If this is your first attempt to use the Assimilator, it is also possible that you do not have a JavaScript enabled browser, or that you have not turned on the switch to enable JavaScript execution. On most browsers, you can enable JavaScript in the "Options" or "Preferences" menu. But before checking that, let's try a simple diagnostic test.
You should see two buttons. The first button will attempt to manually launch the Assimilator. If it works (which is doubtful), then you're all set. If not, then nothing will probably be happening. In that case, click on the second button. This will try to run a very simple JavaScript program which checks your computer to determine the type of browser you are using. If nothing happens when you click this button, then JavaScript is not working at all, and you probably need to figure out how to enable your browser. If it works, then a small screen should pop up which lists several items of information. This means that JavaScript is enabled - and the Assimilator problem is due to something else. Email the popup information to me (davehall@rotoguru2.com), and provide a concise description of your problem, and we'll see what can be done. (Make sure you've tried a forced server reload first - see the bold blue instructions above.)