I use for add images to categories this plugin: Categories Images
<div class="grid row kategoria"> <?php foreach (get_terms('kategoria') as $cat) : ?> <div class="col-xs-12 col-sm-6 col-md-3"> <a class="cat-link" href="<?php echo get_term_link($cat->slug, 'kategoria'); ?>"> <figure class="effect-ming"> <img src="<?php echo z_taxonomy_image_url($cat->term_id); ?>" /> <figcaption> <h2 class="kategoria"><?php echo $cat->name; ?></h2> <p class="hover hide"><?php echo $cat->name; ?></p> </figcaption> </figure> </a> </div> <?php endforeach; ?> </div>