Thumbnails/icons for categories in sidebar

Hi, could you tell me how can i add icons for each category in sidebar?

Marius and folk might have better answer, but generally you would need to find a plugin, or do some custom coding work for that; since you’d need to be able to setup icons in the post meta, and then call those icons from the meta info for a custom query in the sidebar, and not use the standard WordPress widget.

You may find this useful:
http://codex.wordpress.org/Customizing_Your_Sidebar

However, I seem to recall a plugin somewhere that let you assign an image or icon to each category then call that from a sidebar widget.

Maybe this?
https://wordpress.org/plugins/wpcustom-category-image/

Hi Christopher!
Thank you for your answer. Before to ask i tryed a several plugins, but none of them worked. I found how to do the icons manually, but i didn’t know where i should place additional code for theme. I need the icons in my sidebar which is on every post and categories, but not page. So if i got it right to do any changes in sidebar which is on category page in need to change category.php. But what is about post pages? Do i need loop-single file or something else?

Eventually i could add the icons using one more plugin, but i still wonder how i can change, for instance, background images of sidebars, headers, menus and stuff like this.
Lucian wrote here https://forum.tagdiv.com/topic/control-of-widget-headerslines-on-sidebar/#post-19605 that in order to customize sidebar in categories i need to add a special class to category.php and then customize this class. But i still wait for his answer about customizing other things, coz it’s not easy on my own to understand which file is responsible for what, it’s not the only one css file here…