Text slider - need help with a custom code

[storePS]

Hi there, I tried to add some custome code I found to build a text-slider. 
I created a new section and put this code in:

<!-- Slideshow container -->
<div class="slideshow-container">

<!-- Full-width slides/quotes -->
<div class="mySlides">
<q>I love you the more in that I believe you had liked me for my own sake and for nothing else</q>
<p class="author">- John Keats</p>
</div>

<div class="mySlides">
<q>But man is not made for defeat. A man can be destroyed but not defeated.</q>
<p class="author">- Ernest Hemingway</p>
</div>

<div class="mySlides">
<q>I have not failed. I've just found 10,000 ways that won't work.</q>
<p class="author">- Thomas A. Edison</p>
</div>

<!-- Next/prev buttons -->
<a class="prev" onclick="plusSlides(-1)">&#10094;</a>
<a class="next" onclick="plusSlides(1)">&#10095;</a>
</div>

<!-- Dots/bullets/indicators -->
<div class="dot-container">
<span class="dot" onclick="currentSlide(1)"></span>
<span class="dot" onclick="currentSlide(2)"></span>
<span class="dot" onclick="currentSlide(3)"></span>
</div>

/* Slideshow container */
.slideshow-container {
position: relative;
background: #f1f1f1f1;
}

/* Slides */
.mySlides {
display: none;
padding: 80px;
text-align: center;
}

/* Next & previous buttons */
.prev, .next {
cursor: pointer;
position: absolute;
top: 50%;
width: auto;
margin-top: -30px;
padding: 16px;
color: #888;
font-weight: bold;
font-size: 20px;
border-radius: 0 3px 3px 0;
user-select: none;
}

/* Position the "next button" to the right */
.next {
position: absolute;
right: 0;
border-radius: 3px 0 0 3px;
}

/* On hover, add a black background color with a little bit see-through */
.prev:hover, .next:hover {
background-color: rgba(0,0,0,0.8);
color: white;
}

/* The dot/bullet/indicator container */
.dot-container {
text-align: center;
padding: 20px;
background: #ddd;
}

/* The dots/bullets/indicators */
.dot {
cursor: pointer;
height: 15px;
width: 15px;
margin: 0 2px;
background-color: #bbb;
border-radius: 50%;
display: inline-block;
transition: background-color 0.6s ease;
}

/* Add a background color to the active dot/circle */
.active, .dot:hover {
background-color: #717171;
}

/* Add an italic font style to all quotes */
q {font-style: italic;}

/* Add a blue color to the author */
.author {color: cornflowerblue;}

{% javascript %}

var slideIndex = 1;
showSlides(slideIndex);

function plusSlides(n) {
showSlides(slideIndex += n);
}

function currentSlide(n) {
showSlides(slideIndex = n);
}

function showSlides(n) {
var i;
var slides = document.getElementsByClassName("mySlides");
var dots = document.getElementsByClassName("dot");
if (n > slides.length) {slideIndex = 1}
if (n < 1) {slideIndex = slides.length}
for (i = 0; i < slides.length; i++) {
slides[i].style.display = "none";
}
for (i = 0; i < dots.length; i++) {
dots[i].className = dots[i].className.replace(" active", "");
}
slides[slideIndex-1].style.display = "block";
dots[slideIndex-1].className += " active";
}
{% endjavascript %}

unfortunately it doesn't work, the section does not appear on my website, no chance to add this custom section. 
I don't know what I did wrong. 
Can somebody please help me?
Thanks 🙂