I want to add extra column in magebto admin user, how can i add.[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/WbXRW.png

I need to add phone number for the admin users how can i add?


I added like this in /app/code/core/Mage/Adminhtml/Block/Api/User/Grid.php


        <?php
    /**
     * Magento
     *
     * NOTICE OF LICENSE
     *
     * This source file is subject to the Open Software License (OSL 3.0)
     * that is bundled with this package in the file LICENSE.txt.
     * It is also available through the world-wide-web at this URL:
     * http://opensource.org/licenses/osl-3.0.php
     * If you did not receive a copy of the license and are unable to
     * obtain it through the world-wide-web, please send an email
     * to [email protected] so we can send you a copy immediately.
     *
     * DISCLAIMER
     *
     * Do not edit or add to this file if you wish to upgrade Magento to newer
     * versions in the future. If you wish to customize Magento for your
     * needs please refer to http://www.magento.com for more information.
     *
     * @category    Mage
     * @package     Mage_Adminhtml
     * @copyright  Copyright (c) 2006-2017 X.commerce, Inc. and affiliates (http://www.magento.com)
     * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
     */
    
    /**
     * Adminhtml permissions user grid
     *
     * @category   Mage
     * @package    Mage_Adminhtml
     * @author      Magento Core Team <[email protected]>
     */
    class Mage_Adminhtml_Block_Api_User_Grid extends Mage_Adminhtml_Block_Widget_Grid
    {
    
        public function __construct()
        {
            parent::__construct();
            $this->setId('permissionsUserGrid');
            $this->setDefaultSort('username');
            $this->setDefaultDir('asc');
            $this->setUseAjax(true);
        }
    
        protected function _prepareCollection()
        {
            $collection = Mage::getResourceModel('api/user_collection');
            $this->setCollection($collection);
            return parent::_prepareCollection();
        }
    
        protected function _prepareColumns()
        {
            $this->addColumn('user_id', array(
                'header'    => Mage::helper('adminhtml')->__('ID'),
                'width'     => 5,
                'align'     => 'right',
                'sortable'  => true,
                'index'     => 'user_id'
            ));
    
            $this->addColumn('username', array(
                'header'    => Mage::helper('adminhtml')->__('User Name'),
                'index'     => 'username'
            ));
    
            $this->addColumn('firstname', array(
                'header'    => Mage::helper('adminhtml')->__('First Name'),
                'index'     => 'firstname'
            ));
    
            $this->addColumn('lastname', array(
                'header'    => Mage::helper('adminhtml')->__('Last Name'),
                'index'     => 'lastname'
            ));
    
            $this->addColumn('email', array(
                'header'    => Mage::helper('adminhtml')->__('Email'),
                'width'     => 40,
                'align'     => 'left',
                'index'     => 'email'
            ));
    
            $this->addColumn('mobile', array(
                'header'    => Mage::helper('adminhtml')->__('Mobile'),
                'width'     => 40,
                'align'     => 'left',
                'index'     => 'mobile'
            ));
    
            $this->addColumn('is_active', array(
                'header'    => Mage::helper('adminhtml')->__('Status'),
                'index'     => 'is_active',
                'type'      => 'options',
                'options'   => array('1' => Mage::helper('adminhtml')->__('Active'), '0' => Mage::helper('adminhtml')->__('Inactive')),
            ));
    
            return parent::_prepareColumns();
        }
    
        public function getRowUrl($row)
        {
            return $this->getUrl('*/*/edit', array('user_id' => $row->getId()));
        }
    
        public function getGridUrl()
        {
            //$uid = $this->getRequest()->getParam('user_id');
            return $this->getUrl('*/*/roleGrid', array());
        }
    
    }


But it is not working.