all you need to do is look at the databases for each program, then make a form with the user input, then make the php script as follows:
<?
//form variables
$username = $_REQUEST[username];
$password = $_REQUEST[password];
//add or edit to fit your needs
$server = "localhost"; //server with database
$db_user = "test"; //username for database
$db_pass = "test"; //password for database
$success_url = "thankyou.html"; //url to redirect user after registration is successful.
$conn = mysql_connect($server,$db_user,$db_pass);
$adduser = mysql_db_query("program1","INSERT INTO `users`
(`id`,
`username`,
`password`)
VALUES (NULL,
'$username',
'$password')");
$adduser2 = mysql_db_query("program2","INSERT INTO `users`
(`id`,
`username`,
`password`)
VALUES (NULL,
'$username',
'$password')");
//change above to fit your needs
if ($adduser && $adduser2) {
header('Refresh: 1; url='.$success_url);
echo 'The user was created successfully! You will be redirected shortly';
} //redirect user if successful.
else {
echo 'The user was NOT created successfully! Please go <a href="javascript: history.back(1)">back</a> and try again';
} //dont redirect, but display an error message.
?>
if you need any help on this, let me know.