I had posted a question regarding disk management - someone while helping me, wanted me to post screen shot of Gparted - screen shot is gathered by me, but while replying his comments, I am not able to attach that file - I need answer how to do the same?
As a general rule, if someone asks you for a clarification of your question/answer, you shouldn't answer them in a comment. You should instead edit your original post. That's precisely why there is no way to include screenshots or other media in comments. Comments are second class citizens here. They are ephemeral and limited in scope. Everything should be done in answers and questions.
So, next time a situation like this arises, don't try to answer with a comment. Edit your post and then leave a comment to whoever asked for clarifications informing them that you have made an edit.