PHP - Slideshow Won't Display In Content Window

I've been working on developing a CMS blog and now I'm trying to create a slideshow wit Bootstrap Carousel on the homepage to present the dynamic content (images + text) using the data from table 'posts'.

I tested this code, and it only presents one post. I mean, It's not possible to go to the next slide. I want to show all the posts on the slides.

*The DB connection is already on the includes. The connection was written on a small file called DB.php

Home.php

<header>
          <div id="carouselExampleIndicators" class="carousel slide" data-ride="carousel">
                  <ol class="carousel-indicators">
                    <li data-target="#carouselExampleIndicators" data-slide-to="0" class="active"></li>
                    <li data-target="#carouselExampleIndicators" data-slide-to="1"></li>
                    <li data-target="#carouselExampleIndicators" data-slide-to="2"></li>
                  </ol>
                  <div class="carousel-inner" role="listbox">
              <?php
              // The default SQL query
                  $sql = "SELECT * FROM posts ORDER BY id desc";
                  $stmt = $ConnectingDB->query($sql);
                    while ($DataRows = $stmt->fetch()) {
                      $Id = $DataRows["id"];
                      $PostTitle = $DataRows["title"];
                      $Image = $DataRows["image"];
                      $PostText = $DataRows["post"];
              ?>
                    <!-- Slide -->
                    <div class="carousel-item active" style="background-image: url('uploads/<?php echo $Image; ?>')">
                      <div class="carousel-caption">
                        <div class="card-body black">
                          <h3 class="large-mistral-white"><?php echo $PostTitle; ?></h3>
                          <p class="small-times-white"><?php echo $PostText; ?></p>
                        </div>
                      </div>
                    </div>
                    <?php } ?>
                  </div>
                  <a class="carousel-control-prev" href="#carouselExampleIndicators" role="button" data-slide="prev">
                    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
                    <span class="sr-only">Previous</span>
                  </a>
                  <a class="carousel-control-next" href="#carouselExampleIndicators" role="button" data-slide="next">
                    <span class="carousel-control-next-icon" aria-hidden="true"></span>
                    <span class="sr-only">Next</span>
                  </a>
                </div>
        </header>

DB.php

<?php

$DSN='mysql:host = localhost; dbname=everybody_blog';
$ConnectingDB = new PDO($DSN,'root','');
?>

Most of the websites I have built have not been large and not dynamic in nature, but I need to make one now with a boatload of content on it. and I’m needing a little resource help where I can research something. I’m sure all developers do this, and I know I need a massive database or 2 and the PHP knowledge I already have, but I’m just looking for a little guidance about how to do this the easiest way. It may actually sound like a stupid question and I might be over-thinking a bit. So…

Lets say I have 500 articles that I want to make available to a site visitor and give them the option to choose what they want to look at through nav menus and submenus. I want the same page to display to the user, regardless of what article is chosen.  how does PHP play a part in that? Would I be right by saying the following?

If the home page had this content on it:

This website is a course in PHP coding. <a href="courseTemplate.php" target="_blank">Click here</a> to view course #1.

and I wanted all the course content to be displayed through the use of the “courseTemplate.php” file, how simple is that? I would assume that these types of things would be the results and the techniques to accomplish the goal, right?

=> a resulting URL that looks like this:

www.site.com/courseTemplate.php?id=1

=> storing all the text of the course material in one single field of a DB record. NOT storing the layout-oriented code (HTML, etc.) and echoing it out with the rest of the text.

=> making use of the GET() function somehow to pull the course’s text content out of the database.

Can someone show me a website that demonstrates this? I don’t think this is very difficult, and I’m sure there are web resources available that show how this is done. I’m almost sure that most news agency websites do this, and I know for a fact that most forum software has this template technique written into it, regardless if SEO is included or not. Sorry for the basic nature of this question. I know some of my previous posts have been such where I’ve asked much more difficult questions than this. I have seen youtube tutorials on issues similar to this, but nothing pulled up by google really shows this in a very simplistic nature. thanks.