wordpress full post featured image not showing

sorry i forget to add image link click below link

https://smg.photobucket.com/user/MKRayden/media/pic2_zps48c59c51.png.html

https://smg.photobucket.com/user/MKRayden/media/pic1_zps57f25ee6.png.html

Install PHP Code Widget then activate. On the widgets page, add a PHP Code Widget on the Before Content widget area. Add code:

<?php the_post_thumbnail( 'full' ); ?>

thanks sir 1 more thing could you please tell me how do i add comment on author profile page