call and display a text file from a php file - php

Question

I have the following php file which displays this webpage
Everything inside the black box is from a text file called questions.txt, that is called from the php file with the below code:
I wish to call and display (in the same format, like a black bordered box) some introductory text with images and possible iframes like youtube videos) just before the questions.
In the code below I've included it as a comment # ...have tried various things but it hasn't worked.
The file needs to be called and displayed under "Test your Knowledge" and above the start of the questions.
<!-- Main
============================================= -->
<section id="code">
<div class="container-fluid" style="text-align:center;">
<p></br></br></br></br></p>
<div class="row">
<div class="col-lg-2 text-left">
<p></br></br></br></br></p>
<?php include 'quiz-sidebar.php'; ?>
</div>
<div class="col-lg-10 text-center">
<h2 class="section-heading" style="color:black;">Test Your Knowledge : <?php include "content/quiz/". $_GET['quiz'] ."/title.txt"; ?></h2>
<p></br></p>
#I want to call and display a txt file here (called introtext.txt), in the same format as below, but just as text
<div style="border-style: solid; border-radius: 5px; border-width: 5px;">
<p></p>
<form method="POST" action="<?php echo "quiz-result.php?quiz=".$_GET['quiz']; ?>">
<?php
$loadedQuestions = readQuestions("content/quiz/". $_GET['quiz'] ."/questions.txt");
displayTheQuestions($loadedQuestions);
?>
<input type="submit" name="submitquiz" value="Submit Quiz"/>
</form>
<p></p>
</div>
<p></br></br></br></br></p>
</div></div>
</div>
</section>
Can someone please include in my original code an explanation and fix for how to call and display a text file (or another php file) inside this one, in the position desired.
I'd also like to format the text of the questions to make them left-aligned (have posted that in another question)
I have tried various things but they haven't worked:
1. include('questiontrinket.php') (I included it as below) but it just showed up as plain text rather than rendering the file
<h2 class="section-heading" style="color:black;">Test Your Knowledge : <?php include "content/quiz/". $_GET['quiz'] ."/title.txt"; ?></h2>
<p></br></p>
<?php include('introtext.php') ?>
...didn't work
2. I also tried the following
<?php
echo file_get_contents( "introtext.php" ); // get the contents, and echo it out.
?>
This didn't work either

Answer 1

The following code works fine for me
<!-- Main
============================================= -->
<section id="code">
<div class="container-fluid" style="text-align:center;">
<p><br><br><br><br></p>
<div class="row">
<div class="col-lg-2 text-left">
<p><br><br><br><br></p>
<?php include 'quiz-sidebar.php'; ?>
</div>
<div class="col-lg-10 text-center">
<h2 class="section-heading" style="color:black;">Test Your Knowledge : <?php include "content/quiz/". $_GET['quiz'] ."/title.txt"; ?></h2>
<p><br></p>
<!-- I want to call and display a txt file here (called introtext.txt), in the same format as below, but just as text -->
<?php include 'introtext.php'; ?>
<div style="border-style: solid; border-radius: 5px; border-width: 5px;">
<p></p>
<form method="POST" action="<?php echo "quiz-result.php?quiz=".$_GET['quiz']; ?>">
<?php
$loadedQuestions = readQuestions("content/quiz/". $_GET['quiz'] ."/questions.txt");
displayTheQuestions($loadedQuestions);
?>
<input type="submit" name="submitquiz" value="Submit Quiz"/>
</form>
<p></p>
</div>
<p><br><br><br><br></p>
</div>
</div>
</div>
</section>