How can I allow visitors to post a reply on an Article/News Item?

How can I get it so visitors to my site can leave a comment on any given article. At this time it seems only users can leave comments.

Please and Thank you!

Go into the Administration Panel>>Modules>>Articles, then make sure there is a tick on the "Allow comments for articles".

If your visitors (Non Members) still cannot post comments, then go again into the Administration Panel>>Settings>>Membership Levels and on the "Level" area, click on "Action" for the kind of users you would like to allow this option (you mentioned "visitors", so this corresponds to "Non Member"), put a tick on "Comments Vote" and then click on "Enable".

That's it

Edit:

You have to follow an identical procedure for the other module, "News".

Yes, perfect! Thank you soooo much for your reply! Your second option was what I needed to do and had no clue to do that! Thank you again!