How to make the contact form submit responses to email?

I want to make the contact form to submit the responses when the user hits the submit button. Upon the user hitting the submit button, it should also redirect them to thankyou.html which I have already accomplished. But the responses should also be emailed to me, and I am stuck on that part and cannot figure it out in the php file.

PHP File:

<?php
$errors = '';
$myemail = 'm.hussainomer03@gmail.com';//<-----Put Your email address here.
if(empty($_POST['name'])  ||
   empty($_POST['email']) ||
   empty($_POST['message']))
{
    $errors .= "\n Error: all fields are required";
}
$name = $_POST['name'];
$email_address = $_POST['email'];
$message = $_POST['message'];
if (!preg_match(
"/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/i",
$email_address))
{
    $errors .= "\n Error: Invalid email address";
}

if( empty($errors))
{
$to = $myemail;
$email_subject = "Contact form submission: $name";
$email_body = "You have received a new message. ".
" Here are the details:\n Name: $name \n ".
"Email: $email_address\n Message \n $message";
$headers = "From: $myemail\n";
$headers .= "Reply-To: $email_address";
mail($to,$email_subject,$email_body,$headers);
//redirect to the 'thank you' page
header('Location: contact-form-thank-you.html');
}
?>

Rest Of The Code:

input[type=text], [type=email], select, textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid #ccc;
  margin-top: 6px;
  margin-bottom: 16px;
  resize: vertical;
}

input[type=submit] {
  background-color: rgb(62, 3, 179);
  color: white;
  padding: 12px 20px;
  border: none;
  cursor: pointer;
}

input[type=submit]:hover {
  background-color: deeppink;
}


.contactform {
  position: relative;    
  border-radius: 50px;
  background-color: #f2f2f2;
  padding: 5px;
  z-index:2;
  display: block;
  margin-left: auto;
  margin-right: auto;
  margin-bottom:auto;
  margin-top:1%;    
  width: 100%;
  animation-name: gradient;
  animation-duration: 3s;
  animation-iteration-count: infinite;  
    
}
    
.contactform:hover { 
 animation-name: gradient;
 animation-duration: 15s;
 animation-iteration-count: infinite;    
    
   
}


.column {
  float: center;
  width: 50%;
  margin-top: 6px;
  padding: 20px;
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 40%;
    
}

.row:after {
  content: "";
  display: table;
  clear: both;
}

@media screen and (max-width: 600px) {
  .column, input[type=submit] {
    width: auto;
    margin-top:0;
  }
}

<section id="contact">
  <div class="container" data-aos="fade-up">
    <div class="contactform">
      <div style="text-align:center">
        <div class="section-title">
          <h2><br/>Get In Touch</h2>
        </div>
        <p>Feel Free To Reach Out To Me Through This Form! </p>
      </div>
      <div class="row">
        <div class="column">
          <form name="myform" action="contact.php" method="POST">
            <label for="firstname">First Name</label>
            <input type="text" id="firstname" name="firstname" placeholder="Your name.." required>

            <label for="lastname">Last Name</label>
            <input type="text" id="lastname" name="lastname" placeholder="Your last name.." required>

            <label for="email">Email:</label>
            <input type="email" id="email" name="email" placeholder="Your Email.." required>

            <label for="subject">Subject</label>
            <textarea id="subject" name="subject" placeholder="Lets Collaborate..." style="height:170px" required></textarea>
            <input type="submit" value="Submit">
          </form>
        </div>
      </div>
    </div>
  </div>
</section>

What I tried essentially before was to rename the classes/objects in the php file but that did not do the trick either.

from How to make the contact form submit responses to email?