Trying to create a custom registration page for a theme,

Hello,

Trying to create a custom registration page for a theme, i have created the custom login and registration but the way it is now, its not how i want it. i want it to be able to allow users to enter the name of the site they wished to create just like when using the default WP wp-signup.php file. Don't know if u get what am saying. here's what i have.

<?php
							  			require_once(ABSPATH . WPINC . '/registration.php');
										global $wpdb, $user_ID;
										//Check whether the user is already logged in
										if ($user_ID) {

										    // They're already logged in, so we bounce them back to the homepage.

										   wp_redirect(home_url() );

										} else {

										    $errors = array();

										    if( $_SERVER['REQUEST_METHOD'] == 'POST' ) {

										        // Check username is present and not already in use
										        $username = $wpdb->escape($_REQUEST['username']);
										        if ( strpos($username, ' ') !== false ) {
										            $errors['username'] = "Sorry, no spaces allowed in usernames";
										        }
										        if(empty($username)) {
										            $errors['username'] = "Please enter a username";
										        } elseif( username_exists( $username ) ) {
										            $errors['username'] = "Username already exists, please try another";
										        }

										        // Check email address is present and valid
										        $email = $wpdb->escape($_REQUEST['email']);
										        if( !is_email( $email ) ) {
										            $errors['email'] = "Please enter a valid email";
										        } elseif( email_exists( $email ) ) {
										            $errors['email'] = "This email address is already in use";
										        }

										        // Check password is valid
										        if(0 === preg_match("/.{6,}/", $_POST['password'])){
										          $errors['password'] = "Password must be at least six characters";
										        }

										        // Check password confirmation_matches
										        if(0 !== strcmp($_POST['password'], $_POST['password_confirmation'])){
										          $errors['password_confirmation'] = "Passwords do not match";
										        }

										        // Check terms of service is agreed to
										        if($_POST['terms'] != "Yes"){
										            $errors['terms'] = "You must agree to Terms of Service";
										        }

										        if(0 === count($errors)) {

										            $password = $_POST['password'];

										            $new_user_id = wp_create_user( $username, $password, $email );

										          		// send an email to the admin alerting them of the registration
														wp_new_user_notification($new_user_id);

														// log the new user in
														wp_setcookie($user_login, $user_pass, true);
														wp_set_current_user($new_user_id, $user_login);
														do_action('wp_login', $user_login);

														// send the newly created user to the home page after logging them in

										            $success = 1;
										 			wp_redirect(home_url()); exit;
										           // header( 'Location:/signin/?success=1&u=' . $username );

										        }

										    }
										}
							  		?><form id="wp_signup_form" action="<?php echo $_SERVER['REQUEST_URI']; ?>" method="post">

									        <label for="username">Username</label>
									        <input type="text" name="username" id="username">
									        <label for="email">Email address</label>
									        <input type="text" name="email" id="email">
									        <label for="password">Password</label>
									        <input type="password" name="password" id="password">
									        <label for="password_confirmation">Confirm Password</label>
									        <input type="password" name="password_confirmation" id="password_confirmation">

									        <input name="terms" id="terms" type="checkbox" value="Yes">
									        <label for="terms">I agree to the Terms of Service</label>

									        <input type="submit" id="submitbtn" name="submit" value="Sign Up" />

									</form>