How do I display the author and his/her picture in the post

For the picture:

<?php echo get_avatar( get_the_author_email(), 'size here' ); ?>

For the name:

<?php the_author_posts_link(); ?>

Hi,

Thanks for the reply. Which file(s) should I edit to add those lines?

index.php –> To show name/picture on homepage
single.php –> To show name/picture on each post page

Thank you very much for your help with this, do77.