Hi Norma, if you are talking about the little round icon and the little rectangle, the info is in the How to use Forum Features thread.
The circle icon is blue if there are no new post to that thread, it is red if the are new post, if there is a star in it is means you have posted in that thread, if the lines are scrolling it means it is a popular thread with more than 25 post.
The little rectangle if clicked will take you to the newest post since you were last in that thread.