Difficultly in using site

I am totally confused. I received a response to my question
asking for more information but I have no idea how I
can response to the sender.
Sheila P

Hit ‘Reply’.

You’ve seem to have been able to do it before in your topic: Virus warnings from an unknown source op

As mentioned, by Rundvleeskroket .

You don’t have to respond directly to the sender, as mentioned just hit the Reply in the post that you want to reply to.