If you are using profile picture plugin. then you need to just put simple code to upload and show profile picture.
Place below code on the user-profile.php - make sure this code is place OUTSIDE of the existing form on that page - this function will allow users to upload their profile picture
<?php profile_picture_upload(); ?>
Place below code on pages you wish to show the profile picture, including user-public-profile.php and item.php
<?php profile_picture_show(); ?>
Then it will work better!!!!