Add filed in profile users - Listbingo

How can add the fileds to complite in the users profile?
I just added the code for view the field's box in the profile but when i writing in it the data don't save in the database.

I added this code in the profile.defoult.php:

<div>
<label id="telmsg" for="tel"><?php echo JText::_('TEL');?></label>
<input name="tel" type="text" id="tel" value="<?php echo $this->profile->tel;?>" />
</div>

<div>
<label id="faxmsg" for="fax"><?php echo JText::_('FAX');?></label>
<input name="fax" type="text" id="fax" value="<?php echo $this->profile->fax;?>" />
</div>

but when i write in this box the date don't store in the database!
Can you help me? Thank you!