Получите Templete Uri
<img src="<?php echo get_template_directory_uri(); ?>/images/logo.png" width="" height="" alt="" />
Black Heart
<img src="<?php echo get_template_directory_uri(); ?>/images/logo.png" width="" height="" alt="" />
/* get logo or image */
<img src="<?php echo get_template_directory_uri(); ?>/images/logo.png" width="" height="" alt="" />
include( get_template_directory_uri() . '/includes/my_file.php' );
<img src="<?php echo get_template_directory_uri(); ?>/images/logo.png" width="" height="" alt="" />