PHP Code in UPFRONT Child Theme

I am just fooling around with Spirit to try and get the hang of it. I am trying to duplicate a page that I have created in another theme. At the top of this page I have the users Avatar and their Nickname. I achieved this by adding this code to the header.php file of the child theme...

<div class="site-avatar"><h3> <!--?php echo get_blog_avatar( get_current_blog_id(), 48 ); ?-->
        <!--?php the_author_meta( 'nickname' ); ?--></h3></div>

I cannot seem to figure out how to duplicate this in Upfront. It seems that the code editor has everything but PHP which is what the page is built with so I find that very odd. Am I missing something?