Add columns using Bootstrap code

Copy the code below for the columns that you would like to display and paste it into the Text portion.

<div class="row">
  <div class="col-xs-12 col-sm-6 col-md-8">Content for 2/3 area goes here...</div>
  <div class="col-xs-6 col-md-4">Content for 1/3 area goes here...</div> 
</div>

<div class="row">
 <div class="col-xs-6 col-sm-4">Content for 1/3 area goes here...</div>
 <div class="col-xs-6 col-sm-4">Content for 1/3 area goes here...</div>
 <!-- Optional: clear the XS cols if their content doesn't match in height -->
 <div class="clearfix visible-xs-block"></div> 
 <div class="col-xs-6 col-sm-4">Content for 1/3 area goes here...</div> 
</div>

<div class="row">
 <div class="col-xs-6">Content for 1/2 area goes here...</div>
 <div class="col-xs-6">Content for 1/2 area goes here...</div>
</div>

Then go back to Visual mode and edit the content from there.