Adding a Field in Admin/ Users

I’m quite the newbie in coding and I have been trying to add a field to admin users area. Name should be ‘phone’. also, I’m trying to set up an automated email system where two users when paired would receive email with other users email address. it’s currently in actns_post.php file and looks like this:

$res3 = get_bid_info($_GET['winner']);
				choose_winner($pid, $_GET['winner']);

				$post_id_7 = get_post($pid);
				$title = $post_id_7->post_title;

				//-- send mails

				$winbd = $res3['userid'];
				$user_info = get_userdata($winbd);
				$to = $user_info->user_email;
                                $unm = $user_info->user_login;

				//-- seller details

				global $current_user;
				get_currentuserinfo();
				$curr  = $current_user->ID;

				$user_info2 = get_userdata($curr);
				$sel  = $user_info2->user_email;
                                $unm2 = $user_info2->user_login;

				$em = 'Hi '.$unm.'<br/> Your bid('.get_currency().$res3['bid'].')
				has been chosen as a winner to the auction: <b><a href="'.get_permalink($pid).'">'.$title.'</a></b><br><br>';
				$em .= 'Here is the client

s email: <b>'.$sel.'</b>

You can contact your client at the above address.';
				$em .= '

Thank you for using our services';

				$em2 = 'Hi '.$unm2.' Your have chosen the bid('.get_currency().$res3['bid'].')
				as a winner to your auction: <b><a href="'.get_permalink($pid).'">'.$title.'</a></b>

';
				$em2 .= 'Here is the contractor

s email: <b>'.$sel.'</b>

You can contact your contractor at the above address.';
				$em2 .= '

Thank you for using our services';

				// email to bidder
				send_mail($em,'', $to,'Your bid has been chosen as a winner');
				send_mail($em2,'',$sel,'Winner chosen for your project auction');

			   ?>

I need to add the phone number to this option. I’ve already created the table for phone number in registration page. I think I would also need to create a data base table somewhere.
Anyone have any ideas? Please help, I’m pretty stuck in here.