http://abron.eu/wp/product-category/relay-group/
for example:
I want relay group description add to this page, before the pictures.
Some themes may show it, but the vast majority do not. I personally use the category descriptions for my benefit, not site visitors.
If you paid for the premium Ken theme, you might get the quickest answer from the theme developer:
http://themeforest.net/item/the-ken-multipurpose-creative-wordpress-theme-/7281173/support
However, assuming that the theme does not display category info by default, you’re probably looking at a child-theme situation. I ALWAYS use child themes, even with premium themes, since your changes will be protected when the “parent” theme is updated.
http://codex.wordpress.org/Child_Themes
Once you get your child theme up and running, adding the category info can be accomplished by copying and modifying the template(s) used for the pages and posts where you want the info displayed. You may need to modify the style.css file to adjust the styling if desired.
http://codex.wordpress.org/Child_Themes#Template_Files