WordPress Functions adding Author Box?

I’m new to wordpress and I was able to customize this plugin a little but now I’m trying to add the author box below the posts. When I try and use the code below it throws error saying the functions are not found. How do I include the path to the wordpress functions. Is this something to do with my template?

[ Moderator Note: Please post code or markup snippets between backticks or use the code button. ]

<div class="about-author">
    <figure class="author-photo">
        <?php echo get_avatar( get_the_author_meta('ID') , 80 ); ?>
    </figure>
    <div class="ovh">
        <div class="author-description">
            <h6><?php the_author_posts_link(); ?></h6>
            <p><?php the_author_meta('description'); ?></p>
        </div>

        <?php if ($options["links_box_disp"]) {?>

        <div class="post-links">

<ul>
<li><a>"><?php _e('All posts', 'crum'); ?></a></li>
<li><a>" rel="author" ><?php _e('Website', 'crum'); ?></a></li>
<li><a>" title="E-mail"><?php _e('Email', 'crum');?></a></li>
</ul>
        </div>

        <?php } ?>

        <div class="share-icons">
            <?php if (get_the_author_meta('twitter')) {  echo '<a href="',the_author_meta('twitter'),'"><i class="icon-twitter-bird"></i></a>';  } ?>
            <?php if (get_the_author_meta('cr_facebook')) {  echo '<a href="',the_author_meta('cr_facebook'),'"><i class="icon-facebook-rect"></i></a>';  } ?>
            <?php if (get_the_author_meta('googleplus')) {  echo '<a href="',the_author_meta('googleplus'),'"><i class="icon-googleplus-rect"></i></a>';  } ?>
            <?php if (get_the_author_meta('linkedin')) {  echo '<a href="',the_author_meta('linkedin'),'"><i class="icon-linkedin-rect"></i></a>';  } ?>
            <?php if (get_the_author_meta('vimeo')) {  echo '<a href="',the_author_meta('vimeo'),'"><i class="icon-vimeo"></i></a>';  } ?>
            <?php if (get_the_author_meta('lastfm')) {  echo '<a href="',the_author_meta('lastfm'),'"><i class="icon-lastfm"></i></a>';  } ?>
            <?php if (get_the_author_meta('tumblr')) {  echo '<a href="',the_author_meta('tumblr'),'"><i class="icon-tumblr"></i></a>';  } ?>
            <?php if (get_the_author_meta('skype')) {  echo '<a href="',the_author_meta('skype'),'"><i class="icon-skype"></i></a>';  } ?>
            <?php if (get_the_author_meta('vkontakte')) {  echo '<a href="',the_author_meta('vkontakte'),'"><i class="icon-vkontakte-rect"></i></a>';  } ?>
            <?php if (get_the_author_meta('deviantart')) {  echo '<a href="',the_author_meta('deviantart'),'"><i class="icon-deviantart"></i></a>';  } ?>
            <?php if (get_the_author_meta('picasa')) {  echo '<a href="',the_author_meta('picasa'),'"><i class="icon-picasa"></i></a>';  } ?>
            <?php if (get_the_author_meta('wordpress')) {  echo '<a href="',the_author_meta('wordpress'),'"><i class="icon-wordpress"></i></a>';  } ?>
            <?php if (get_the_author_meta('instagram')) {  echo '<a href="',the_author_meta('instagram'),'"><i class="icon-instagram"></i></a>';  } ?>

        </div>
    </div>
</div>

https://www.ads-software.com/plugins/display-posts-shortcode/