Somewhere in single.php file, you should have this portion of code :
<?php if(have_posts()) : ?>
<?php while(have_posts()) : the_post(); ?>
This is the loop, once a post exists for the post URL, it displays the post.
Then you should see this kind of code :
<h3 id="post-<?php the_ID(); ?>" <?php post_class(); ?>><?php the_title(); ?>...</h3>
This is the post title.
You can try to add DATE, TIME and AUTHOR's NAME by adding this just after/below the poste title :
<span class="date">Posted on <?php the_time('F j, Y'); ?> at <?php the_time('g:i a'); ?></span>
<span class="author">Writen by <?php the_author(); ?></span>