if you want to do it simply without using a database, you need a static html page with a form in it and a password field with name="password" in it. the action of the form should point to a php page.

the page of php it points to will need something like this in it (you can put this code anywhere in the page):

<?
$password = $_REQUEST[password];

if ($password == "foo") {
?>
here is some web content for people who know that the password is foo
<?
} elseif ($password == "bar") {
?>
here is some web content for people who know that the password is bar
<?
} else {
?>
here is some web content for all the other schmucks
<?
}
?>
please note, this is quick and dirty but it works and should get you started in the right direction for writing more complex stuff. experiment with it and see where it gets you. the web content can be any html including images, tables links etc or it could contain just a row or two of a table that starts before the quoted code and ends after it. as i said, play with it, see where it gets you and feel free to ask me for help.

i've got a working version of this file running here. you can point a form to it and test it if you like.