Alrighty…
First off, you’re going to need to change the extention of index.html to index.php (Be sure to update any links you have on your site to index.html ;))
Next, because we want to keep this as simple as possible, create a file in same directory where index.php is located and call it status.txt You’ll need to be sure that this file is writeable by the webserver. (That means to change it’s mode to 644 or 664 or 666, one of those should work. You can change the file’s mode in your ftp client.)
Next, create the file status.php and paste this as its contents:
<?php
$passwd = 'YOUR PASSWORD'; //Change this value!!
if (isset($_POST'submit']))
{
if ($_POST'passwd'] == $passwd)
{
$fp = fopen('status.txt', 'w');
fwrite($fp, $_POST'status']);
fclose($fp);
} else {
echo '<b>Invalid Password!!</b><hr />';
}
}
?>
<html>
<body>
<h3>Change Status</h3>
<form action="status.php" method="post">
Password: <input type="password" name="passwd" />
<br />
Status:
<select name="status">
<option value="off" selected>Off</option>
<option value="on">On</option>
</select>
<br />
<input type="submit" name="submit" value="Update Status" />
</form>
</body>
</html>
Change the YOUR_PASSWORD to what you would like the status updateing password to be. (Leave the ’ ’ around your password, but you don’t enter them when you enter your password.) Whenever you want to change your on-air status, go to http://www.billfredinthenighttime.com/status.php, enter your password, pick the new status, and click update.
Next, insert the php code below in the spot in your index.php file where you want to display your status. For example:
..... <a href="aboutbillfred.html">about Billfred</a> | <a href="aboutbitn.html">about BitN</a> | <a href="oldnews.html">older news</a> | <a href="links.html">links</a> | <a href="downloads.html">downloads</a> | <a href="http://wusc.sc.edu">WUSC</a>
<br><br> <?php
$status = trim(strtolower(file_get_contents('status.txt')));
switch ($status)
{
case 'on':
?>
PUT HTML FOR 'ON' HERE
<?php
break;
default:
?>
PUT HTML FOR 'OFF' HERE
<?php
}
?>..... Uhm, hi.<br><br>
If you're reading this, you've obviously found my website. Sucker--erm, <i>lucky you!</i><br><br>
Change the PUT HTML FOR blah… to whatever html you would like to display for your on or off status.
This isn’t the most graceful way of updateing your status, but it’s pretty quick and very functional. If ya have any questions, ask and someone should be able to help 
Jack
PS: If you would rather have your status change automatically depending on the date/time, you could have that instead.