How to add "Featured Image" to categories

Hi,

Could you please help me with adding "Featured Image" to the category?
I have two pages:
TV Room: http://wowdesigns.in/projects/xyz/tv-room/
Survey: http://wowdesigns.in/projects/xyz/survey/

And one Category post:
Reading Room: http://wowdesigns.in/projects/xyz/category/reading-room/

Since TV Room and Survey are pages I had an option to add the header images.
Where as Reading Room is post(where I need to display articles) I don't have a option to add "Featured image" as it is category.

I used this plugin https://wordpress.org/plugins/categories-images/ Added image as well, but I am unable to fetch image.
Could you please help me with this, I am stuck with this for quite sometime.
Thanks much.