form class

Hi!
I have one problem with class in form generator. I'm using bootstrap-form. Curenty I get this output:

Code:

---

<div class="widget widget-email form-group">
<div class="input-group"><div class="input-group-addon"><span class="glyphicon glyphicon-envelope"></span></div>
<input class="text kuverta form-control" type="email" name="frm2_Email" id="ctrl_16" placeholder="Vpišite vaš e-Poštni naslov">
</div>

---

My wish it's additional class in the first div. It's must be class or id from input field. "kuverta" or "ctrl_16".

Code:

---

<div class="HERE-IT'S-MY-VALUE widget widget-email form-group">
<div class="input-group"><div class="input-group-addon"><span class="glyphicon glyphicon-envelope"></span></div>
<input class="text kuverta form-control" type="email" name="frm2_Email" id="ctrl_16" placeholder="Vpišite vaš e-Poštni naslov">
</div>

---