Edit in JSFiddle

<main>
  <section class="fixed bg1">
    <div class="container">
      <h1>Fixed position</h1>
      <p>background-image</p>
    </div>
  </section>
  <section class="scrolling">
    <div class="bg">
      <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Dolore incidunt suscipit similique, dolor corrupti cumque qui consectetur autem laborum fuga quas ipsam doloribus sequi, mollitia, repellendus sapiente repudiandae labore rerum amet culpa inventore, modi non.</p>
    </div>
  </section>
  <section class="fixed bg2"></section>
  <section class="scrolling">
    <div class="bg">
      <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Dolore incidunt suscipit similique, dolor corrupti cumque qui consectetur autem laborum fuga quas ipsam doloribus sequi, mollitia, repellendus sapiente repudiandae labore rerum amet culpa inventore, modi non.</p>
    </div>
  </section>
  <section class="fixed bg3">
  </section>
  <section class="scrolling">
    <div class="bg">
      <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Dolore incidunt suscipit similique, dolor corrupti cumque qui consectetur autem laborum fuga quas ipsam doloribus sequi, mollitia, repellendus sapiente repudiandae labore rerum amet culpa inventore, modi non.</p>
    </div>
  </section>
  <section class="fixed bg4"></section>
  <section class="scrolling">
    <div class="bg">
      <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Dolore incidunt suscipit similique, dolor corrupti cumque qui consectetur autem laborum fuga quas ipsam doloribus sequi, mollitia, repellendus sapiente repudiandae labore rerum amet culpa inventore, modi non.</p>
    </div>
  </section>
</main>

main {
  height: 100vh;
}
.scrolling {
  > .bg {
    transform: skewY(-4.5deg);
    background-color: #F6F4DB;
    margin: -50px auto;
    padding: 10px 0;

  > p {
      transform: skewY(4.5deg);
      width: 60%;
      margin: 60px auto;
      font-size: 25px;
    }
  }
}
.fixed {
  height: 100%;
  background-size: cover;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-position: center center;
  
  &.bg1 { background-image: url(//www.pakutaso.com/shared/img/thumb/ELFADSC08949_TP_V.jpg); }
  &.bg2 { background-image: url(//www.pakutaso.com/shared/img/thumb/ELFASIMG_1983_TP_V.jpg); }
  &.bg3 { background-image: url(//www.pakutaso.com/shared/img/thumb/TSURU170321-45%20mm-096_TP_V.jpg); }
  &.bg4 { background-image: url(//www.pakutaso.com/shared/img/thumb/hirota_sabanna_TP_V.jpg); }
}

.fixed.bg1 {
  position: relative;
  
  > .container {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 90%;
    transform: translateX(-50%) translateY(-50%);
    text-align: center;
    color: white;
    
    > h1 {
      font-size: 70px;
      margin: 0;
    }
    > p {
      font-size: 30px;
    }
  }
}