<div class="grid-container">
  <div class="grid-item item1">1 / 4 / 1 / 1</div>
  <div class="grid-item item2">b</div>
  <div class="grid-item item3">5/span 3</div>
</div>

.grid-container {
  display: grid;
  grid-template-areas:  'a a a a'
                        'f b b b' 
                        'c c d d'
                        'e e e e';
  grid-template-rows: repeat(4, 1fr);
  grid-template-columns: repeat(4, 1fr);
  height: 200px;
  padding: 10px;
  background-color: #ccc;
}

.grid-item {
  margin: 3px;
  padding: 10px;
  background-color: yellow;
}

.item1 {
  grid-area: 1 / 4 / 1 / 1
}

.item2 {
  grid-area: b;
}

.item3 {
  grid-area: 4 / span 3;
}