How to answer to responses to my own thread

It is purely technical question.  I got two responses to my thread.  I would like to react to them, but I do not know how to do it.  When I click "Action" I am getting a message: "No actions are available".  What is the reason that I was able to open a thread, but I have no possibility to participate in the discussion.

SolidworksDrawings And Detailing