How do I reply to an answer I got on here just now?

Or after you pick the news feed button, there is another button labeled "Activity" selecting that will show all discussions you have contributed to.

Salbee, do you know which discussion thread you want to answer it?
A quick way for me is: On the top right is a box: MY ACCOUNT.
Right below it is: NEWS FEED.
Click on NEWS FEED, scroll to the discussion thread you want to respond to, click on it. And then you can answer.

You go to the box that says Answer this Question and type your reply there and then press post comment.