How to send back a page with php

How do I send back the failure and success page?
Can I just load a new body onto the page?

I have templates for failure and success but I am not sure how to load them onto my page.

<?php
 //this will load the mustache template library
 require_once 'mustache/mustache/src/Mustache/Autoloader.php';
 Mustache_Autoloader::register();

 // this will create a new mustache template engine
 $mustache = new Mustache_Engine;

 // these lines load your header, footer, and body template into strings
 $header = file_get_contents('templates/header.html');
 $body = file_get_contents('templates/emailform.html');
 $footer = file_get_contents('templates/footer.html');

 // this will be used to send the page title into the page
 $header_data = ["pagetitle" => "Contact"];

 //this is being used to send a footer title and local time to the footer
 $footer_data = [
     "localtime" => date('l jS \of F Y h:i:s A'),
     "footertitle" => "Contact"];

     echo $mustache->render($header, $header_data) . PHP_EOL;
     echo $mustache->render($body) . PHP_EOL;
     echo $mustache->render($footer, $footer_data) .  PHP_EOL;
// up to here I am loading my contact form page

 function successpage() {
     /* ********************************************
      * HOW TODO THIS (erase this comment when you are done)
      * ********************************************
      * write your success page here. you need to use templating
      * so you need to add the mustache library above where indicated.
      * Write this part to send back a page.
      */
 }

 function failurepage() {
     /* ********************************************
      * HOW TODO THIS (erase this comment when you are done)
      * ********************************************
      * write your failure page here. you need to use templating
      * so you need to add the mustache library above where indicated.
      * Write this part to send back a page.
      */
 }



 function main() {
     /* This will test to make sure we have a non-empty $_POST from
      * the form submission. */
     if (!empty($_POST)) {
         /* ********************************************
          * I need TODO  this part as well, but I am first trying to send back the page first.
          * ********************************************
          * Do your validation and cleaning here. You need to extract FOUR
          * things from the $_POST array...
            $name --> trim it, strip HTML tags, and sub-string it to 64
            $subject --> trim it, strip HTML tags, and sub-string it to 64
            $message --> trim it, strip HTML tags, and sub-string it to 1000
            $from --> look up and use the PHP filter_var() with FILTER_VALIDATE_EMAIL
            https://www.php.net/manual/en/function.filter-var.php
          *
          */


         if (!empty($name) && !empty($from) && !empty($subject) && !empty($message)) {

             /* this forms the correct email headers to send an email */
             $headers = "From: $from\r\n";
             $headers .= "Reply-To: $from\r\n";
             $headers .= "MIME-Version: 1.0\r\n";
             $headers .= "Content-type: text/plain; charset=iso-8859-1\r\n";
             if (mail(/****fill out the paramters here****/)) {
                 successpage();
             } else {
                 failurepage();
             }
         } else {
             failurepage();
         }
     } else {
         failurepage();
     }
 }

 // this kicks off the script
 main();

Hi Kasstover,

We may need more information - is this a freecodecamp challenge you can link us too or a project you’re working on yourself?