I have the plugin Profile Builder (https://wordpress.org/plugins/profile-builder/) installed and on the registration fields when signing up I have a field that asks you for your first name, the meta name is 'first_name'. I don't know much more.
I have this code here on member-header.php where it displays the users username:
<h2 class="user-nicename"><?php bp_displayed_user_username(); ?></h2>
How would I echo the first name field (first_name) instead?