At K2 forum admin has advised me to make it what way:
"You must create an extra field of type "Link" or "Textarea" and then render this field in your template. Of course this requires to create a template override. You can read more regarding K2 template overrides at getk2.org/documentation/tutorials/174-te...pts-of-sub-templates ."
I need the code for overrides. Could somebody write how to make It the advised way or another?