How to stop URL editing

[ZoundZ]

This is my first post, so hello.

 

I was hoping someone had an idea on how to do this, because even though I'm a decent with PHP, I have no idea how it's done.  I want to make it so people can enter in my website URL(like this : www.mysite.com/) , but, I want to make it so that if they enter in something after the slash(like this: mysite.com/blah.php) they get an error.  Anyone know how this can be done?  I want them to access blah.php, but only by a link on my website, not by entering it in themselves.

 

 

Thanks in advance for any help I receive.

[papaface]

$page = "http://www.domain.com";
if ($_SERVER['HTTP_REFERER'] != $page)
{
exit;
}
else
{
//page
}

[ZoundZ]

Well, that stops people from going to any page other than the index page.  I want them to be able to go to it, I just don't want them to be able to go to it by editing the URL.  So, if they're clicking links, they can go to it.