Can You Tag a Facebook Status After Posting?by C. Taylor
To tag a Facebook status after posting, you need the ability to edit the status update. If you included an image in the original post, an edit option appears, so you can retroactively tag the status update; status updates without a photo are not editable. If you didn't include an image in the original post, you can delete the post and create a new one, but you'll lose all the comments on the first post. A better alternative is to simply add a comment that tags the person.
Status Updates With Pictures
Click the photo or date in the posted status update.
Click "Edit" in the right pane of the picture window.
Click the "Who Were You With" field and begin typing the friend's name. Click the full name from the suggestion list. Alternatively, type "@" followed by the friend's name within the body of the status update and select the friend from the suggestion list that appears.
Click "Done Editing" and then the "X" in the picture window.
Status Updates Without Pictures
Click "Comment" under the status update.
Type "@" followed by the friend's name. Suggestions automatically appear as you type the name.
Click the friend's name to add the tag.
Press "Enter" to post the tagged comment.