How to wrap every slide in to a div with a class ?

Something from this

<section id="slide-org793f6fd" class=grid-wrapper">
  <h2 id="org793f6fd">Trigger Warning</h2>
  <p>Some of the theory mentioned below might exclude or grouped some people from some gender groups.</p>
</section>

To this

<section id="slide-org793f6fd" >
  <div class=grid-wrapper">
      <h2 id="org793f6fd">Trigger Warning</h2>
      <p>Some of the theory mentioned below might exclude or grouped some people   from some gender groups.</p>
  </div>
</section>