<div class="menu">home</div>
<div class="menu current">about</div>
<div class="menu">Contact</div>

.current:after {
  content: '';
  position: absolute;

  width: 0;
  height: 0;

  border: 15px solid;
  border-top-color: #292929;

  top: 100%;
  left: 50%;
  margin-left: -15px; /* adjust for border width */
}

.menu {
Font: whatever;
Background:url("image/parallel.PNG");
}
.current {
Background:URL("image/arrow.PNG");
}

<div class="menu">home</div>
<div class="menu current">about</div>