Responding to a Friend’s Post
When a friend posts something to his Wall or News Feed, it typically appears in your News Feed, unless your friend kept you out of the loop (by limiting how much of his information you can see via his privacy settings). You can then read the update, post a comment on it, “like” it (give it the thumbs up), and even share the update with your other friends.
Posting a Comment
The most common response to a friend’s status update, other than ignoring it completely or just reading it, is to comment on it. Click the Comment link just below the message, type your comment in the box that appears, and click the Comment button.
Whatever you write as a comment will be viewable by all of your friend’s Facebook friends ...