Adding custom fields to registration popup

I am trying to add custom fields to the registration popup. I have read threads such as but it never works.

Apparently I am suppose to add something similar to this to functions.php:

add_action( 'coursepress_after_all_signup_fields', 'custom_field_cp_signup' );
function custom_field_cp_signup() {
$location = isset($_POST['student_location']) ? $_POST['student_location'] : null;
$field_2 = isset($_POST['example_field_2']) ? $_POST['example_field_2'] : null;
<label class="cp_popup_col_2">
                        <input type="text" name="student_location" class="" id="cp_popup_student_location" value="<?php echo $location; ?>" />
<label class="cp_popup_col_2">
                        <input type="text" name="example_field_2" class="" id="example_field_2" value="<?php echo $location; ?>" />

Which functions.php does that go into? /wp-content/plugins/coursepress/themes/coursepress/functions.php? I've added it there. Am I now suppose to see these two input fields (student_location & example) on my registration popup at (click SIGNUP!)? Because I see nothing.

How do I get these new fields onto my registration popup and save them to the Students/Users table in the WordPress Admin? I've copied my functions.php to if you want to see (the bottom) of it.

Thanks for any help.