Setting background Image of a row

Since 4 days I am finding a way to apply parallax effect to a div. So I wanted to set a background image of a row which contains 4 columns like below. But I am in-vain. I can customize each column's style but unable to customize the row style.

<div class="my-custom-background">

<{{ wrapper }}{{ attributes }}>
{{ title_suffix.contextual_links }}

  {% if col_first.content %}
    <{{ col_first.wrapper }}{{ col_first.attributes }}>
      {{ col_first.content }}
    </{{ col_first.wrapper }}>
  {% endif %}

  {% if col_second.content %}
    <{{ col_second.wrapper }}{{ col_second.attributes }}>
      {{ col_second.content }}
    </{{ col_second.wrapper }}>
  {% endif %}

  {% if col_third.content %}
    <{{ col_third.wrapper }}{{ col_third.attributes }}>
      {{ col_third.content }}
    </{{ col_third.wrapper }}>
  {% endif %}

  {% if col_fourth.content %}
    <{{ col_fourth.wrapper }}{{ col_fourth.attributes }}>
      {{ col_fourth.content }}
    </{{ col_fourth.wrapper }}>
  {% endif %}

</{{ wrapper }}>
</div>