それを自分で試してみてください

<!DOCTYPE html>
<html>
<title>W3.CSS</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="/lib/w3.css">
<body>

<div class="w3-display-container mySlides">
  <img src="img_fjords.jpg" style="width:100%">
  <div class="w3-display-bottomleft w3-large w3-container w3-padding-hor-16 w3-black">
    Trolltunga, Norway
  </div>
</div>

<div class="w3-display-container mySlides">
  <img src="img_lights.jpg" style="width:100%">
  <div class="w3-display-bottomright w3-large w3-container w3-padding-hor-16 w3-black">
    Northern Lights, Norway
  </div>
</div>

<div class="w3-display-container mySlides">
  <img src="img_mountains.jpg" style="width:100%">
  <div class="w3-display-topleft w3-large w3-container w3-padding-hor-16 w3-black">
    Beautiful Mountains
  </div>
</div>

<div class="w3-display-container mySlides">
  <img src="img_forest.jpg" style="width:100%">
  <div class="w3-display-topright w3-large w3-container w3-padding-hor-16 w3-black">
    The Rain Forest
  </div>
</div>

<div class="w3-display-container mySlides">
  <img src="img_mountains.jpg" style="width:100%">
  <div class="w3-display-middle w3-large w3-container w3-padding-hor-16 w3-black">
    Mountains!
  </div>
</div>

</div>

function plusDivs(n) {
  showDivs(slideIndex += n);
}

</body>
</html>