Many many thanks.
I've put that like this
<title>Selecting MySQL Database</title>
<?php echo phpinfo(); ?>
$dbhost = 'localhost:3306';
$dbuser = 'created_user';
$dbpass = 'password';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
die('Could not connect: ' . mysql_error());
echo 'Connected successfully';
mysql_select_db( 'created_user' );
this is called index.html and it's put in D:\xampp\htdocs\mysite2
But when I call this http://localhost/mysite2, I still see nothing.
At the same time, I have another set of site programs in D:\xampp\htdocs\mysite and I can locate to the starting page of that, by http://localhost/mysite.