Adds display name settings to MemberPress

memberpress-display-name.php

<?php
/*
Plugin Name: MemberPress Display Name
Plugin URI: https://memberpress.com
Description: Adds a Display Name field to MemberPress signup and account pages
Version: 1.0
Author: Caseproof, LLC
Author URI: http://caseproof.com/
Copyright: 2004-2014, Caseproof, LLC
*/

function mpdn_show_on_registration() {
  ?>
    <div class="mp-form-row">
      <div class="mp-form-label">
        <label>Display Name Publically As:*<br/><small>Must be different than your username and email address</small></label>
      </div>
      <input type="text" name="mepr_user_display_name" id="mepr_user_display_name" class="mepr-form-input mepr-display-name" value="<?php echo (isset($_POST['mepr_user_display_name']) && !empty($_POST['mepr_user_display_name']))?stripslashes($_POST['mepr_user_display_name']):''; ?>" />
    </div>
  <?php
}
add_action('mepr-after-password-fields', 'mpdn_show_on_registration', 9);

function mpdn_validate_registration($errors) {
  $mepr_options = MeprOptions::fetch();

  //Ignore logged in users
  if(MeprUtils::is_user_logged_in()) { return $errors; }

  if(empty($_POST['mepr_user_display_name'])) {
    $errors[] = "You must enter a Public Display Name";
    return $errors;
  }

  if($mepr_options->username_is_email) {
    if(stripslashes($_POST['user_email']) == stripslashes($_POST['mepr_user_display_name'])) {
      $errors[] = "Your Public Display Name must be different than your Email Address";
    }
  }
  else {
    if(stripslashes($_POST['user_email']) == stripslashes($_POST['mepr_user_display_name'])) {
      $errors[] = "Your Public Display Name must be different than your Email Address";
    }
    if(stripslashes($_POST['user_login']) == stripslashes($_POST['mepr_user_display_name'])) {
      $errors[] = "Your Public Display Name must be different than your Username";
    }
  }

  return $errors;
}
add_filter('mepr-validate-signup', 'mpdn_validate_registration');

function mpdn_save_registration($txn) {
  //If it's not set, let's bail - something's wrong or the user is already logged in
  if(!isset($_POST['mepr_user_display_name'])) { return; }

  $display_name = stripslashes($_POST['mepr_user_display_name']);
  $user = new MeprUser($txn->user_id);

  if(isset($user->ID) && (int)$user->ID > 0) {
    $user->display_name = $display_name;
    $user->store();

    //Set the nickname to the display name also, why not?
    update_user_meta($user->ID, 'nickname', $display_name);
  }
}
add_action('mepr-signup', 'mpdn_save_registration');

function mpdn_show_on_account($user) {
  ?>
    <div class="mp-form-row">
      <div class="mp-form-label">
        <label>Display Name Publically As:*<br/><small>Must be different than your username and email address</small></label>
      </div>
      <input type="text" name="mepr_user_display_name" id="mepr_user_display_name" class="mepr-form-input mepr-display-name" value="<?php echo $user->display_name; ?>" />
    </div>
  <?php
}
add_action('mepr-account-home-fields', 'mpdn_show_on_account');

function mpdn_validate_on_account($errors, $user) {
  if(!isset($_POST['mepr_user_display_name']) || empty($_POST['mepr_user_display_name'])) {
    $errors[] = "You must enter a Public Display Name";
    return $errors;
  }

  $display_name = stripslashes($_POST['mepr_user_display_name']);
  $new_email    = stripslashes($_POST['user_email']);
  $old_email    = $user->user_email;
  $username     = $user->user_login;

  if($display_name == $new_email || $display_name == $old_email) {
    $errors[] = "Your Public Display Name cannot be the same as your Email Address";
  }
  if($display_name == $username) {
    $errors[] = "Your Public Display Name cannot be the same as your Username";
  }

  return $errors;
}
add_filter('mepr-validate-account', 'mpdn_validate_on_account', 11, 2);

function mpdn_save_account($user) {
  $display_name = stripslashes($_POST['mepr_user_display_name']);
  $user->display_name = $display_name;
  $user->store();

  //Set the nickname to the display name also, why not?
  update_user_meta($user->ID, 'nickname', $display_name);
}
add_action('mepr-save-account', 'mpdn_save_account');

Hi, where I can add this php file? thankypu