I don't quite understand what you mean by " run a banner." Does it need to be a scrolling banner, and does it have to be Javascript?
Marquees will work fine for that, but only in IE.

To change the colour of the background, I'd just use an onClick or an :bou::bou::bou::bou::bou::bou::bou:Over event.

As for the browser and browser version info, you can use navigator.appName and navigator.appVersion, respectively.

Here is a little page I threw together in about five minutes; I'm not sure if it's at all what you're trying to do though. I'd happily change it for you though.

<div style="font-size: 11px;">
<pre>
&lt;html>
&lt;head>
&lt;title>hi2u&lt;/title>
&lt;style type="text/css">
body { font-family: Tahoma, Verdana;
color: 9b89bd;
}
&lt;/style>
&lt;/head>

&lt;body bgcolor="#000000">

&lt;center>
&lt;a style="color: 68569a; font-family: Tahoma, Verdana; font-size: 20px; cursor: hand;" onClick="document.bgColor='white';">Change the background colour&lt;/a>
&lt;br>&lt;br>&lt;br>
&lt;a style="color: 68569a; font-family: Tahoma, Verdana; font-size: 20px; cursor: hand;" onClick="document.bgColor='black';">Change it back&lt;/a>
&lt;br>&lt;br>
&lt;center>

&lt;script type="text/javascript">
var name = navigator.appName
var ver = navigator.appVersion
document.write
("You are using " + name + ", " + ver + ".");
&lt;/script>

&lt;marquee scrollamount="7" width="100%" direction="left">Hi there.&lt;/marquee>
&lt;marquee scrollamount="7" width="100%" direction="right">This only works&lt;/marquee>
&lt;marquee scrollamount="7" width="100%" direction="left">in IE.&lt;/marquee>

&lt;/body>
&lt;/html>
</pre>
</div>