elitel on "Additional Custom Field in Register Page with my sample idea."

/**
 * Template Name: Registration Page
 *
 */

if ( 'POST' == $_SERVER['REQUEST_METHOD'] && !empty( $_POST['action'] ) && $_POST['action'] == 'adduser' ) {
	$user_pass = wp_generate_password();
	<strong>$userdata</strong> = array(
		'user_pass' => $user_pass,
		'user_login' => esc_attr( $_POST['user_name'] ),
		'first_name' => esc_attr( $_POST['first_name'] ),
		'last_name' => esc_attr( $_POST['last_name'] ),
		'nickname' => esc_attr( $_POST['nickname'] ),
		'user_email' => esc_attr( $_POST['email'] ),
		'user_url' => esc_attr( $_POST['website'] ),
		'aim' => esc_attr( $_POST['aim'] ),
		'yim' => esc_attr( $_POST['yim'] ),
		'jabber' => esc_attr( $_POST['jabber'] ),
		'description' => esc_attr( $_POST['description'] ),
		'role' => get_option( 'default_role' ),
	);
}
<form method="post" style="display: block; clear: both;" id="adduser" class="user-forms"
action="http://<?php echo $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']; ?>">
<p class="first_name">
<label for="first_name"><?php _e('First Name', 'frontendprofile'); ?></label>
<input class="text-input" name="first_name" type="text" id="first_name" value="<?php if ( $error ) echo esc_html( $_POST['first_name'], 1 ); ?>" required  />
</p><!-- .first_name -->

<p class="last_name">
<label for="last_name"><?php _e('Last Name', 'frontendprofile'); ?></label>
<input class="text-input" name="last_name" type="text" id="last_name" value="<?php if ( $error ) echo esc_html( $_POST['last_name'], 1 ); ?>" required />
</p><!-- .last_name -->

<p class="form-submit">
<?php echo $referer; ?>
<input name="adduser" type="submit" id="addusersub" class="submit button" value="<?php if ( current_user_can( 'create_users' ) ) _e('Add User', 'frontendprofile'); else _e('Register', 'frontendprofile'); ?>" />
<?php wp_nonce_field( 'add-user' ) ?>
<input name="action" type="hidden" id="action" value="adduser" />
</p><!-- .form-submit -->
</form><!-- #adduser -->

Problem:
1. Additional Custom Fields in the Register Page.
2. How to Create Additional Database Columns and How to insert it's values?

Here's what I think should be edited to solve my issues.
In $user_data, can I add the new fields in the array such as :
e.g.,

$userdata = array(
    'user_has_reference_one' => esc_attr($_POST['ref_one']),
    'user_has_reference_two' => esc_attr($_POST['ref_two']),
    'user_has_reference_three' => esc_attr($_POST['ref_three'])
)

And for the Input fields to be displayed in the form.. I Should add :

<p class="ref_one">
<label for="last_name"><?php _e('First Reference', 'ref_one'); ?></label>
<input class="text-input" name="ref_one" type="text" id="ref_one" value="<?php if ( $error ) echo esc_html( $_POST['ref_one'], 1 ); ?>" required />
</p>

I'm not really sure if I'm on the right track. I am a WP newbie. Please help.
And I can't see any insert query. Thank you.