menambah feature image

<?php
// menambah feature image
add_theme_support( 'post-thumbnails' );
//set_post_thumbnail_size( 150, 150);

// Image size for single index
// add_image_size( 'thumbnail', 150, 150 );

// Image size for single posts
//add_image_size( 'single-post-thumbnail', 590, 180 );