WPyogi on "Prana child theme footer problem"

I try to copy the footer.php there into the child's theme style.css folder nothing happens.

No, because that's not where footer.php code goes. If you have FTP access set up, you need to use that to upload a copy of the footer.php file to the child theme folder. So you will have:

wp-content
     themes
         prana
         pranachild
            style.css
            footer.php

And then modify the footer.php file. This is the current footer.php code:

<div id="footer">
    <div class="container_16">
      <?php do_action( 'prana_footer' ); ?>
    </div>
  </div>

</div> <!-- end .wrapper -->
<?php wp_footer(); ?>
</body>
</html>

It IS possible to modify that file - start by using this for the footer.php file in your child theme:

<div id="footer">
    <div class="container_16">
      <div id="myfooter">
         PUT YOUR CODE HERE
      </div>
    </div>
  </div>

</div> <!-- end .wrapper -->
<?php wp_footer(); ?>
</body>
</html>