First of all, please edit About us module and change:
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    <figure data-fb="https://www.facebook.com/gavickpro" data-twitter="https://twitter.com/gavickpro" data-gplus="https://plus.google.com/+gavickpro/posts" class="animate_queue_element">
      <img src="images/demo/about/1.jpg" border="0" alt="Tim Berners" />
      <figcaption>
         <h3>Tim Berners</h3>
         <small>CEO Executive Officer</small> </figcaption>
   </figure>
to:
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    <figure data-text="My sample text" class="animate_queue_element">
      <img src="images/demo/about/1.jpg" border="0" alt="Tim Berners" />
      <figcaption>
         <h3>Tim Berners</h3>
         <small>CEO Executive Officer</small> </figcaption>
   </figure>
Thats the easiest part 

.
Now, please edit file:
/templates/gk_creativity/js/gk.scripts.js
And change:
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             figure.getProperty('data-fb') != null || 
            figure.getProperty('data-twitter') != null || 
            figure.getProperty('data-gplus') != null
to:
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             figure.getProperty('data-fb') != null || 
            figure.getProperty('data-twitter') != null || 
            figure.getProperty('data-gplus') != null
After this code:
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             if(figure.getProperty('data-gplus') != null) {
               htmloutput += '<a href="'+figure.getProperty('data-gplus')+'" data-type="gplus">Google+</a>';
               classcounter++;
            }
add another block:
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             if(figure.getProperty('data-text') != null) {
               htmloutput += '<span>'+figure.getProperty('data-text')+'</span>';
               classcounter++;
            }   
That will generate the text in overlay.
Now the final thing is to add some css'ing to it, but you havent mention anything about it, so just to be general, you can use override.css (please enable it in template settings, advanced section) with this code:
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 .gkTeamOverlay > span {
display: block;
text-align: center;
position: absolute;
top: 64px;
color: #fff;
width: 100%;
font-weight: bold;
}