https://getbootstrap.com/docs/4.3/examples/pricing/

<?php require_once('header.php'); ?>

<div class="container">
<form method="POST" action="processform.php">
  <div class="form-group">
    <label for="exampleInputEmail1">Email address</label>
    <input type="text" name="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Enter email">
  </div>
  <div class="form-group">
    <label for="exampleInputPassword1">Password</label>
    <input type="text" name="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
  </div>
  <div class="form-group form-check">
    <input type="checkbox" class="form-check-input" id="exampleCheck1">
    <label class="form-check-label" for="exampleCheck1">Check me out</label>
  </div>
  <button type="submit" class="btn btn-primary">Submit</button>
</form>
</div>

<?php require_once('footer.php'); ?>

//// --- processform.php --- ///

<?php require_once('header.php');?>
<?php
    $email = $_POST['email'];
    $password = $_POST['password'];
?>

<div class="container">
    <ul>
        <li>Email: <?= $email ;?> </li>
        <li>Password: <?= $password ;?></li>
    </ul>
</div>

<?php require_once('footer.php');?>