<?php

$login = $_POST['login'];

$parol = $_POST['parol'];

if ($login == "admin" && $parol == "admin") {

    echo 'Login parol to\'g\'ri kiritilsa bu matn ko\'rinadi';

} else {

    if (isset($_POST)) { echo '

        <form method="POST" action="bu_kod_yozilgan_sahifa.php">

            login<br /><input type="text" name="login"></input><br/>

            parol<br /><input type="password" name="parol"></input><br/>

            <input type="submit" name="submit" value="Kirish"></input>

        </form>';

    }

}

?>