I need help with my code/Installing CakePHP

Thus, this is my code. I have an h() here which I heard is only allowed with CakePHP. How do I install CakePHP?

<?=
include('app/config/config.php');
error_reporting(E_ALL);
ini_set('display_errors', '1');

while (isset($UserName, $PassPhrase1) && !$_POST['submit']) {
if () {
}
if (h($_POST['submit'])) {
// CakePHP needed
}
}
?><?=
?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Register</title>
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=SUSE:ital,wght@0,100..900;1,100..900&display=swap" rel="stylesheet">
    <style>
        :root {
            --bg: #eef2ff;
            --card: #ffffff;
            --text: #111827;
            --muted: #6b7280;
            --primary: #2563eb;
            --primary-dark: #1d4ed8;
            --border: #cbd5e1;
        }
        * {
            box-sizing: border-box;
        }
        html, body {
            margin: 0;
            min-height: 100%;
        }
        body {
            font-family: 'SUSE', Arial, sans-serif;
            background: linear-gradient(180deg, #e0e7ff 0%, #f8fafc 100%);
            color: var(--text);
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 30px;
        }
        .container {
            width: 100%;
            max-width: 540px;
            background: var(--card);
            border-radius: 28px;
            box-shadow: 0 24px 80px rgba(15, 23, 42, 0.14);
            padding: 36px 32px;
            border: 1px solid rgba(148, 163, 184, 0.16);
        }
        h1 {
            margin: 0 0 16px;
            font-size: 2rem;
        }
        p {
            color: var(--muted);
            margin: 0 0 24px;
            line-height: 1.7;
        }
        .button {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            padding: 14px 20px;
            background: var(--primary);
            color: #fff;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            text-decoration: none;
            font-size: 1rem;
        }
        .button:hover {
            background: var(--primary-dark);
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>Register</h1>
        <p class="subtitle">Create a new account to get started.</p>

        <?php if (!empty($errors)): ?>
            <ul class="message error-list">
                <?php foreach ($errors as $error): ?>
                    <li><?php echo htmlspecialchars($error, ENT_QUOTES, 'UTF-8'); ?></li>
                <?php endforeach; ?>
            </ul>
        <?php endif; ?>

        <form method="post" action="">
            <input type="text" name="username" placeholder="Username" required style="width: 100%; padding: 12px; margin-bottom: 16px; border: 1px solid var(--border); border-radius: 8px;">
            <input type="password" name="password" placeholder="Password" required style="width: 100%; padding: 12px; margin-bottom: 24px; border: 1px solid var(--border); border-radius: 8px;">
            <button type="submit" name="submit" class="button">Register</button>
        </form>
    </div>
</body>
</html>

You could call this a mutex file

The h function in CakePHP is just a convenient wrapper around the htmlspecialchars, which works recursively on arrays, and with handling for objects. If that’s the only thing you need from Cake, just copy it from cakephp/src/Core/functions.php at 9be7d02971f1187ccad6538abb699eceef548065 · cakephp/cakephp · GitHub.